Debate over the atomic bombings of Hiroshima and Nagasaki

Opposition

Militarily unnecessary

Assistant Secretary Bard was convinced that a standard bombardment and naval blockade would be enough to force Japan into surrendering. Even more, he had seen signs for weeks that the Japanese were actually already looking for a way out of the war. His idea was for the United States to tell the Japanese about the bomb, the impending Soviet entry into the war, and the fair treatment that citizens and the Emperor would receive at the coming Big Three conference. Before the bombing occurred, Bard pleaded with Truman to neither drop the bombs (at least not without warning the population first) nor to invade the entire country, proposing to stop the bloodshed.

The 1946 United States Strategic Bombing Survey in Japan, whose members included Paul Nitze, concluded the atomic bombs had been unnecessary to win the war. They said:

There is little point in attempting precisely to impute Japan's unconditional surrender to any one of the numerous causes which jointly and cumulatively were responsible for Japan's disaster. The time lapse between military impotence and political acceptance of the inevitable might have been shorter had the political structure of Japan permitted a more rapid and decisive determination of national policies. Nevertheless, it seems clear that, even without the atomic bombing attacks, air supremacy over Japan could have exerted sufficient pressure to bring about unconditional surrender and obviate the need for invasion.

Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.

This conclusion assumed conventional firebombing would have continued, with ever-increasing numbers of B-29s, and a greater level of destruction to Japan's cities and population. One of Nitze's most influential sources was Prince Fumimaro Konoe, who responded to a question asking whether Japan would have surrendered if the atomic bombs had not been dropped by saying resistance would have continued through November or December 1945.

Historians such as Gentile, Hasegawa, and Newman have criticized Nitze for drawing a conclusion they say went far beyond what the available evidence warranted, in order to promote the reputation of the Air Force at the expense of the Army and Navy.

Dwight D. Eisenhower wrote in his memoir The White House Years:

In 1945 Secretary of War Stimson, visiting my headquarters in Germany, informed me that our government was preparing to drop an atomic bomb on Japan. I was one of those who felt that there were a number of cogent reasons to question the wisdom of such an act. During his recitation of the relevant facts, I had been conscious of a feeling of depression and so I voiced to him my grave misgivings, first on the basis of my belief that Japan was already defeated and that dropping the bomb was completely unnecessary, and secondly, because I thought that our country should avoid shocking world opinion by the use of a weapon whose employment was, I thought, no longer mandatory as a measure to save American lives.

Other U.S. military officers who disagreed with the necessity of the bombings include General of the Army Douglas MacArthur, Fleet Admiral William D. Leahy (the Chief of Staff to the President), Brigadier General Carter Clarke (the military intelligence officer who prepared intercepted Japanese cables for U.S. officials), Fleet Admiral Chester W. Nimitz (Commander in Chief of the Pacific Fleet), Fleet Admiral William Halsey Jr. (Commander of the US Third Fleet), and even the man in charge of all strategic air operations against the Japanese home islands, then-Major General Curtis LeMay:

The Japanese had, in fact, already sued for peace. The atomic bomb played no decisive part, from a purely military point of view, in the defeat of Japan.

— Fleet Admiral Chester W. Nimitz, Commander in Chief of the U.S. Pacific Fleet,

The use of [the atomic bombs] at Hiroshima and Nagasaki was of no material assistance in our war against Japan. The Japanese were already defeated and ready to surrender because of the effective sea blockade and the successful bombing with conventional weapons ... The lethal possibilities of atomic warfare in the future are frightening. My own feeling was that in being the first to use it, we had adopted an ethical standard common to the barbarians of the Dark Ages. I was not taught to make war in that fashion, and wars cannot be won by destroying women and children.

— Fleet Admiral William D. Leahy, Chief of Staff to President Truman, 1950,

The atomic bomb had nothing to do with the end of the war at all.

— Major General Curtis LeMay, XXI Bomber Command, September 1945,

The first atomic bomb was an unnecessary experiment ... It was a mistake to ever drop it ... [the scientists] had this toy and they wanted to try it out, so they dropped it.

— Fleet Admiral William Halsey Jr., 1946,

Stephen Peter Rosen of Harvard believes that a submarine blockade would have been sufficient to force Japan to surrender.

Historian Tsuyoshi Hasegawa wrote the atomic bombings themselves were not the principal reason for Japan's capitulation. Instead, he contends, it was the Soviet entry in the war on 8 August, allowed by the Potsdam Declaration signed by the other Allies. The fact the Soviet Union did not sign this declaration gave Japan reason to believe the Soviets could be kept out of the war. As late as 25 July, the day before the declaration was issued, Japan had asked for a diplomatic envoy led by Konoe to come to Moscow hoping to mediate peace in the Pacific. Konoe was supposed to bring a letter from the Emperor stating:

His Majesty the Emperor, mindful of the fact that the present war daily brings greater evil and sacrifice of the peoples of all the belligerent powers, desires from his heart that it may be quickly terminated. But as long as England and the United States insist upon unconditional surrender the Japanese Empire has no alternative to fight on with all its strength for the honour and existence of the Motherland ... It is the Emperor's private intention to send Prince Konoe to Moscow as a Special Envoy ...

Hasegawa's view is, when the Soviet Union declared war on 8 August, it crushed all hope in Japan's leading circles that the Soviets could be kept out of the war and also that reinforcements from Asia to the Japanese islands would be possible for the expected invasion. Hasegawa wrote:

On the basis of the available evidence, however, it is clear that the two atomic bombs ... alone were not decisive in inducing Japan to surrender. Despite their destructive power, the atomic bombs were not sufficient to change the direction of Japanese diplomacy. The Soviet invasion was. Without the Soviet entry in the war, the Japanese would have continued to fight until numerous atomic bombs, a successful allied invasion of the home islands, or continued aerial bombardments, combined with a naval blockade, rendered them incapable of doing so.

Ward Wilson wrote that "after Nagasaki was bombed only four major cities remained which could readily have been hit with atomic weapons", and that the Japanese Supreme Council did not bother to convene after the atomic bombings because they were barely more destructive than previous bombings. He wrote that instead, the Soviet declaration of war and invasion of Manchuria and South Sakhalin removed Japan's last diplomatic and military options for negotiating a conditional surrender, and this is what prompted Japan's surrender. He wrote that attributing Japan's surrender to a "miracle weapon", instead of the start of the Soviet invasion, saved face for Japan and enhanced the United States' world standing.

Prime Minister Suzuki said in August 1945 that Japan surrendered as quickly as possible to the United States because Japan expected the Soviet Union to invade and hold Hokkaido, an action which would "destroy the foundation of Japan".

Bombings as war crimes

A number of notable individuals and organizations have criticized the bombings, many of them characterizing them as war crimes, crimes against humanity, and/or state terrorism. Early critics of the bombings were Albert Einstein, Eugene Wigner and Leó Szilárd, who had together spurred the first bomb research in 1939 with a jointly written letter to President Roosevelt.

Szilárd, who had gone on to play a major role in the Manhattan Project, argued:

Let me say only this much to the moral issue involved: Suppose Germany had developed two bombs before we had any bombs. And suppose Germany had dropped one bomb, say, on Rochester and the other on Buffalo, and then having run out of bombs she would have lost the war. Can anyone doubt that we would then have defined the dropping of atomic bombs on cities as a war crime, and that we would have sentenced the Germans who were guilty of this crime to death at Nuremberg and hanged them?

A number of scientists who worked on the bomb were against its use. Led by Dr. James Franck, seven scientists submitted a report to the Interim Committee (which advised the President) in May 1945, saying:

If the United States were to be the first to release this new means of indiscriminate destruction upon mankind, she would sacrifice public support throughout the world, precipitate the race for armaments, and prejudice the possibility of reaching an international agreement on the future control of such weapons.

Mark Selden writes, "Perhaps the most trenchant contemporary critique of the American moral position on the bomb and the scales of justice in the war was voiced by the Indian jurist Radhabinod Pal, a dissenting voice at the Tokyo War Crimes Tribunal, who balked at accepting the uniqueness of Japanese war crimes. Recalling Kaiser Wilhelm II's account of his duty to bring World War I to a swift end—"everything must be put to fire and sword; men, women and children and old men must be slaughtered and not a tree or house be left standing". Pal observed:

This policy of indiscriminate murder to shorten the war was considered to be a crime. In the Pacific war under our consideration, if there was anything approaching what is indicated in the above letter of the German Emperor, it is the decision coming from the Allied powers to use the bomb. Future generations will judge this dire decision ... If any indiscriminate destruction of civilian life and property is still illegal in warfare, then, in the Pacific War, this decision to use the atom bomb is the only near approach to the directives of the German Emperor during the first World War and of the Nazi leaders during the second World War.

Selden mentions another critique of the nuclear bombing, which he says the U.S. government effectively suppressed for twenty-five years, as worth mention. On 11 August 1945, the Japanese government filed an official protest over the atomic bombing to the U.S. State Department through the Swiss Legation in Tokyo, observing:

Combatant and noncombatant men and women, old and young, are massacred without discrimination by the atmospheric pressure of the explosion, as well as by the radiating heat which result therefrom. Consequently there is involved a bomb having the most cruel effects humanity has ever known ... The bombs in question, used by the Americans, by their cruelty and by their terrorizing effects, surpass by far gas or any other arm, the use of which is prohibited. Japanese protests against U.S. desecration of international principles of war paired the use of the atomic bomb with the earlier firebombing, which massacred old people, women and children, destroying and burning down Shinto and Buddhist temples, schools, hospitals, living quarters, etc ... They now use this new bomb, having an uncontrollable and cruel effect much greater than any other arms or projectiles ever used to date. This constitutes a new crime against humanity and civilization.

Selden concludes, "the Japanese protest correctly pointed to U.S. violations of internationally accepted principles of war with respect to the wholesale destruction of populations".

In 1963, the bombings were the subject of a judicial review in Ryuichi Shimoda et al. v. The State in Japan. On the 22nd anniversary of the attack on Pearl Harbor, the District Court of Tokyo ruled the use of nuclear weapons was not illegal in war, but issued an opinion in its obiter dictum that the act of dropping any bombs including atomic bombs on cities was at the time governed by the Hague Regulations on Land Warfare of 1907 and the Hague Draft Rules of Air Warfare of 1922–1923 and was therefore illegal.

In the documentary The Fog of War, former U.S. Secretary of Defense Robert McNamara recalls General Curtis LeMay, who relayed the Presidential order to drop nuclear bombs on Japan, said:

"If we'd lost the war, we'd all have been prosecuted as war criminals." And I think he's right. He, and I'd say I, were behaving as war criminals. LeMay recognized that what he was doing would be thought immoral if his side had lost. But what makes it immoral if you lose and not immoral if you win?

As the first combat use of nuclear weapons, the bombings of Hiroshima and Nagasaki represent to some the crossing of a crucial barrier. Peter Kuznick, director of the Nuclear Studies Institute at American University, wrote of President Truman: "He knew he was beginning the process of annihilation of the species." Kuznick said the atomic bombing of Japan "was not just a war crime; it was a crime against humanity".

Takashi Hiraoka, mayor of Hiroshima, upholding nuclear disarmament, said in a hearing to The Hague International Court of Justice (ICJ): "It is clear that the use of nuclear weapons, which cause indiscriminate mass murder that leaves [effects on] survivors for decades, is a violation of international law". Iccho Itoh, the mayor of Nagasaki, declared in the same hearing:

It is said that the descendants of the atomic bomb survivors will have to be monitored for several generations to clarify the genetic impact, which means that the descendants will live in anxiety for [decades] to come ... with their colossal power and capacity for slaughter and destruction, nuclear weapons make no distinction between combatants and non-combatants or between military installations and civilian communities ... The use of nuclear weapons ... therefore is a manifest infraction of international law.

Although bombings do not meet the definition of genocide, some consider the definition too strict, and argue the bombings do constitute genocide. For example, University of Chicago historian Bruce Cumings states there is a consensus among historians to Martin Sherwin's statement, "[T]he Nagasaki bomb was gratuitous at best and genocidal at worst".

The scholar R. J. Rummel instead extends the definition of genocide to what he calls democide, and includes the major part of deaths from the atom bombings in these. His definition of democide includes not only genocide, but also an excessive killing of civilians in war, to the extent this is against the agreed rules for warfare; he argues the bombings of Hiroshima and Nagasaki were war crimes, and thus democide. Rummel quotes among others an official protest from the US government in 1938 to Japan, for its bombing of Chinese cities: "The bombing of non-combatant populations violated international and humanitarian laws." He also considers excess deaths of civilians in conflagrations caused by conventional means, such as in Tokyo, as acts of democide.

In 1967, Noam Chomsky described the atomic bombings as "among the most unspeakable crimes in history". Chomsky pointed to the complicity of the American people in the bombings, referring to the bitter experiences they had undergone prior to the event as the cause for their acceptance of its legitimacy.

In 2007, a group of intellectuals in Hiroshima established an unofficial body called International Peoples' Tribunal on the Dropping of Atomic Bombs on Hiroshima and Nagasaki. On 16 July 2007, it delivered its verdict, stating:

The Tribunal finds that the nature of damage caused by the atomic bombs can be described as indiscriminate extermination of all life forms or inflicting unnecessary pain to the survivors.

About the legality and the morality of the action, the unofficial tribunal found:

The ... use of nuclear weapons in Hiroshima and Nagasaki was illegal in the light of the principles and rules of International Humanitarian Law applicable in armed conflicts, since the bombing of both cities, made civilians the object of attack, using nuclear weapons that were incapable of distinguishing between civilians and military targets and consequently, caused unnecessary suffering to the civilian survivors.

State terrorism

Historical accounts indicate the decision to use the atomic bombs was made in order to provoke a surrender of Japan by use of an awe-inspiring power. These observations have caused Michael Walzer to state the incident was an act of "war terrorism: the effort to kill civilians in such large numbers that their government is forced to surrender. Hiroshima seems to me the classic case." This type of claim eventually prompted historian Robert P. Newman, a supporter of the bombings, to say "there can be justified terror, as there can be just wars".

Certain scholars and historians have characterized the atomic bombings of Japan as a form of "state terrorism". This interpretation is based on a definition of terrorism as "the targeting of innocents to achieve a political goal". As Frances V. Harbour points out, the meeting of the Target Committee in Los Alamos on 10 and 11 May 1945 suggested targeting the large population centers of Kyoto or Hiroshima for a "psychological effect" and to make "the initial use sufficiently spectacular for the importance of the weapon to be internationally recognized". As such, Professor Harbour suggests the goal was to create terror for political ends both in and beyond Japan. However, Burleigh Taylor Wilkins believes it stretches the meaning of "terrorism" to include wartime acts.

Historian Howard Zinn wrote that the bombings were terrorism. Zinn cites the sociologist Kai Erikson who said that the bombings could not be called "combat" because they targeted civilians. Just War theorist Michael Walzer said that while taking the lives of civilians can be justified under conditions of 'supreme emergency', the war situation at that time did not constitute such an emergency.

Tony Coady, Frances V. Harbour, and Jamal Nassar also view the targeting of civilians during the bombings as a form of terrorism. Nassar classifies the atomic bombings as terrorism in the same vein as the firebombing of Tokyo, the firebombing of Dresden, and the Holocaust.

Richard A. Falk, professor emeritus of International Law and Practice at Princeton University has written in detail about Hiroshima and Nagasaki as instances of state terrorism. He said that "the explicit function of the attacks was to terrorize the population through mass slaughter and to confront its leaders with the prospect of national annihilation".

Author Steven Poole said that the "people killed by terrorism" are not the targets of the intended terror effect. He said that the atomic bombings were "designed as an awful demonstration" aimed at Stalin and the government of Japan.

Alexander Werth, historian and BBC Eastern Front war correspondent, suggests that the nuclear bombing of Japan mainly served to demonstrate the new weapon in the most shocking way, virtually at the Soviet Union's doorstep, in order to prepare the political post-war field.

Fundamentally immoral

The Vatican newspaper L'Osservatore Romano expressed regret in August 1945 that the bomb's inventors did not destroy the weapon for the benefit of humanity. Rev. Cuthbert Thicknesse, the Dean of St Albans, prohibited using St Albans Abbey for a thanksgiving service for the war's end, calling the use of atomic weapons "an act of wholesale, indiscriminate massacre". A 1946 report by the Federal Council of Churches entitled Atomic Warfare and the Christian Faith includes the following passage:

As American Christians, we are deeply penitent for the irresponsible use already made of the atomic bomb. We are agreed that, whatever be one's judgment of the war in principle, the surprise bombings of Hiroshima and Nagasaki are morally indefensible.

The bombers' chaplain, Father George Benedict Zabelka, would later renounce the bombings after visiting Nagasaki with two fellow chaplains.

In 2020, Pope Francis, during his visit to Hiroshima, stated the following:

The use of atomic energy for purposes of war is immoral, just as the possessing of nuclear weapons is immoral.

It has never been clearer that, for peace to flourish, all people need to lay down the weapons of war, and especially the most powerful and destructive of weapons: nuclear arms that can cripple and destroy whole cities, whole countries.

Terumi Tanaka, from the survivors' organization of the atomic bomb Nihon Hidankyo, stated the following:

Such inhumane and immoral acts must never be allowed. It is unacceptable to use nuclear weapons in the name of "national security." No state is safe if a nuclear weapon is used, even to protect the survival of a state. Nuclear deterrence, which allows the existence of nuclear weapons based on the possible use of them, goes completely against humanity. The experience of the Hibakusha should be the starting point when discussing the humanitarian impact of nuclear weapons.

Hidankyo received the Nobel Peace Prize in 2024, and Tanaka served as a representative during the ceremony.

Continuation of previous behavior

American historian Gabriel Kolko wrote that certain discussion regarding the moral dimension of the attacks is misguided given that the fundamental moral decision had already been made:

During November 1944 American B-29s began their first incendiary bomb raids on Tokyo, and on 9 March 1945, wave upon wave dropped masses of small incendiaries containing an early version of napalm on the city's population—for they directed this assault against civilians. Soon small fires spread, connected, grew into a vast firestorm that sucked the oxygen out of the lower atmosphere. The bomb raid was a 'success' for the Americans; they killed 125,000 Japanese in one attack. The Allies bombed Hamburg and Dresden in the same manner, and Nagoya, Osaka, Kobe, and Tokyo again on May 24. The basic moral decision that the Americans had to make during the war was whether or not they would violate international law by indiscriminately attacking and destroying civilians, and they resolved that dilemma within the context of conventional weapons. Neither fanfare nor hesitation accompanied their choice, and in fact the atomic bomb used against Hiroshima was less lethal than massive fire bombing. The war had so brutalized the American leaders that burning vast numbers of civilians no longer posed a real predicament by the spring of 1945. Given the anticipated power of the atomic bomb, which was far less than that of fire bombing, no one expected small quantities of it to end the war. Only its technique was novel—nothing more. By June 1945 the mass destruction of civilians via strategic bombing did impress Stimson as something of a moral problem, but the thought no sooner arose than he forgot it, and in no appreciable manner did it shape American use of conventional or atomic bombs. "I did not want to have the United States get the reputation of outdoing Hitler in atrocities", he noted telling the President on June 6. There was another difficulty posed by mass conventional bombing, and that was its very success, a success that made the two modes of human destruction qualitatively identical in fact and in the minds of the American military. "I was a little fearful", Stimson told Truman, "that before we could get ready the Air Force might have Japan so thoroughly bombed out that the new weapon would not have a fair background to show its strength." To this the President "laughed and said he understood".

Nagasaki bombing unnecessary

The atomic bombing of Nagasaki occurred only three days after the bombing of Hiroshima, when the devastation at Hiroshima had yet to be fully comprehended by the Japanese. The lack of time between the bombings has led some historians to state that the second bombing was "certainly unnecessary", "gratuitous at best and genocidal at worst", and not jus in bello. In response to the claim that the atomic bombing of Nagasaki was unnecessary, Maddox wrote:

American officials believed more than one bomb would be necessary because they assumed Japanese hard-liners would minimize the first explosion or attempt to explain it away as some sort of natural catastrophe, which is precisely what they did. In the three days between the bombings, the Japanese minister of war, for instance, refused even to admit that the Hiroshima bomb was atomic. A few hours after Nagasaki, he told the cabinet that "the Americans appeared to have one hundred atomic bombs ... they could drop three per day. The next target might well be Tokyo."

Jerome Hagen indicates that war minister Anami's revised briefing was partly based on interrogating captured American pilot Marcus McDilda. Under torture, McDilda reported that the Americans had 100 atomic bombs and that Tokyo and Kyoto would be the next atomic bomb targets. Both were lies; McDilda was not involved in or briefed on the Manhattan Project and simply told the Japanese what he thought they wanted to hear.

One day before the bombing of Nagasaki, the emperor notified foreign minister Shigenori Tōgō of his desire to "insure a prompt ending of hostilities". Tōgō wrote in his memoir that the emperor "warned [him] that since we could no longer continue the struggle, now that a weapon of this devastating power was used against us, we should not let slip the opportunity [to end the war] by engaging in attempts to gain more favorable conditions". The emperor then requested Tōgō to communicate his wishes to the prime minister.

Dehumanization

Historian James J. Weingartner sees a connection between the American mutilation of Japanese war dead and the bombings. According to Weingartner, both were partially the result of a dehumanization of the enemy: "[T]he widespread image of the Japanese as sub-human constituted an emotional context which provided another justification for decisions which resulted in the death of hundreds of thousands." On the second day after the bombing of Nagasaki, President Truman had stated: "The only language they seem to understand is the one we have been using to bombard them. When you have to deal with a beast you have to treat him like a beast. It is most regrettable but nevertheless true".

Intimidate the Soviets

In 2003, Nelson Mandela, who opposed apartheid in South Africa, said the following about the Hiroshima and Nagasaki bombings:

57 years ago, when Japan was retreating on all fronts, they (U.S.) decided to drop the atom bomb in Hiroshima and Nagasaki. Killed a lot of innocent people, who are still suffering from the effects of those bomb. Those bomb were not aimed against the Japanese. They were aimed against the Soviet Union. To say, look, this is the power that we have. If you dare oppose what we do, this is what is going to happen to you. Because they are so arrogant they decided to kill innocent people in Japan who are still suffering from that.

This statement was made during discussions about the Iraq War. Mandela also stated that the U.S. has committed unspeakable atrocities and is a country that does not care about human beings.

Historian Kai Bird argues that the U.S. had intercepted Japanese diplomatic cables in July 1945 showing that Japan was seeking peace, with the primary condition being the preservation of the emperor system. Despite this, the U.S. proceeded with the bombings. Bird also suggests that the bomb was used partly to send a strategic message to the Soviet Union in the emerging postwar context.

International law

At the time of the atomic bombings, there was no international treaty or instrument protecting a civilian population specifically from attack by aircraft. Many critics of the atomic bombings point to the Hague Conventions of 1899 and 1907 as setting rules in place regarding the attack of civilian populations. The Hague Conventions contained no specific air warfare provisions but it prohibited the targeting of undefended civilians by naval artillery, field artillery, or siege engines, all of which were classified as "bombardment". However, the Conventions allowed the targeting of military establishments in cities, including military depots, industrial plants, and workshops which could be used for war. This set of rules was not followed during World War I which saw bombs dropped indiscriminately on cities by Zeppelins and multi-engine bombers. Afterward, another series of meetings were held at The Hague in 1922–23, but no binding agreement was reached regarding air warfare. During the 1930s and 1940s, the aerial bombing of cities was resumed, notably by the German Condor Legion against the cities of Guernica and Durango in Spain in 1937 during the Spanish Civil War. This led to an escalation of various cities bombed, including Chongqing, Warsaw, Rotterdam, London, Coventry, Hamburg, Dresden, and Tokyo. All of the major belligerents in World War II dropped bombs on civilians in cities.

Modern debate over the applicability of the Hague Conventions to the atomic bombings of Hiroshima and Nagasaki revolves around whether the Conventions can be assumed to cover modes of warfare that were at the time unknown; whether rules for artillery bombardment can be applied to rules for aerial bombing. As well, the debate hinges on to what degree the Hague Conventions was being followed by the warring countries.

If the Hague Conventions is admitted as applicable, the critical question becomes whether the bombed cities met the definition of "undefended". Some observers consider Hiroshima and Nagasaki undefended, some say that both cities were legitimate military targets, and others say that Hiroshima could be considered a legitimate military target while Nagasaki was comparatively undefended. Hiroshima has been argued as not a legitimate target because the major industrial plants were just outside the target area. It has also been argued as a legitimate target because Hiroshima was the headquarters of the regional Second General Army and Fifth Division with 40,000 combatants stationed in the city. Both cities were protected by anti-aircraft guns, which is an argument against the definition of "undefended".

The Hague Conventions prohibited poison weapons. The radioactivity of the atomic bombings has been described as poisonous, especially in the form of nuclear fallout which kills more slowly. However, this view was rejected by the International Court of Justice in 1996, which stated that the primary and exclusive use of (air burst) nuclear weapons is not to poison or asphyxiate and thus is not prohibited by the Geneva Protocol.

The Hague Conventions also prohibited the employment of "arms, projectiles, or material calculated to cause unnecessary suffering". The Japanese government cited this prohibition on 10 August 1945 after submitting a letter of protest to the United States denouncing the use of atomic bombs. However, the prohibition only applied to weapons as lances with a barbed head, irregularly shaped bullets, projectiles filled with glass, the use of any substance on bullets that would tend unnecessarily to inflame a wound inflicted by them, along with grooving bullet tips or the creation of soft point bullets by filing off the ends of the hard coating on full metal jacketed bullets.

It however did not apply to the use of explosives contained in artillery projectiles, mines, aerial torpedoes, or hand grenades. In 1962 and in 1963, the Japanese government retracted its previous statement by saying that there was no international law prohibiting the use of atomic bombs.

The Hague Conventions stated that religious buildings, art and science centers, charities, hospitals, and historic monuments were to be spared as far as possible in a bombardment, unless they were being used for military purposes. Critics of the atomic bombings point to many of these kinds of structures which were destroyed in Hiroshima and Nagasaki. However, the Hague Conventions also stated that for the destruction of the enemy's property to be justified, it must be "imperatively demanded by the necessities of war". Because of the inaccuracy of heavy bombers in World War II, it was not practical to target military assets in cities without damage to civilian targets.

Even after the atomic bombs were dropped on Japan, no international treaty banning or condemning nuclear warfare has ever been ratified. The closest example is a resolution by the UN General Assembly which stated that nuclear warfare was not in keeping with the UN charter, passed in 1953 with a vote of 25 to 20, and 26 abstentions.

Impact on surrender

Varying opinions exist on the question of what role the bombings played in Japan's surrender, and some regard the bombings as the deciding factor, but others see the bombs as a minor factor, and yet others assess their importance as unknowable.

The mainstream position in the United States from 1945 to the 1960s regarded the bombings as the decisive factor in ending the war, which has been termed by commentators as the "traditionalist" view or pejoratively as the "patriotic orthodoxy".

Some, on the other hand, see the Soviet invasion of Manchuria as primary or decisive. In the US, Robert Pape and Tsuyoshi Hasegawa have particularly advanced this view, which some have found convincing, but others have criticized it.

Robert Pape also argues:

Military vulnerability, not civilian vulnerability, accounts for Japan's decision to surrender. Japan's military position was so poor that its leaders would likely have surrendered before invasion, and at roughly the same time in August 1945, even if the United States had not employed strategic bombing or the atomic bomb. Rather than concern for the costs and risks to the population, or even Japan's overall military weakness vis-a-vis the United States, the decisive factor was Japanese leaders' recognition that their strategy for holding the most important territory at issue—the home islands—could not succeed.

In Japanese writing about the surrender, many accounts consider the Soviet entry into the war as the primary reason or as having equal importance with the atomic bombs, and others, such as the work of Sadao Asada, give primacy to the atomic bombings, particularly their impact on the emperor. The primacy of the Soviet entry as a reason for surrender is a longstanding view by some Japanese historians, and it has appeared in some Japanese junior high school textbooks.

The argument about the Soviet role in Japan's surrender has a connection with the argument about the Soviet role in America's decision to drop the bomb. Both arguments emphasize the importance of the Soviet Union. The former suggests that Japan surrendered to the US out of fear of the Soviet Union, and the latter emphasizes that the US dropped the bombs to intimidate the Soviet Union. Soviet accounts of the ending of the war emphasised the role of the Soviet Union. The Great Soviet Encyclopedia summarised events thus:

In August 1945 American military air forces dropped atomic bombs on the cities of Hiroshima (6 August) and of Nagasaki (9 August). These bombings were not caused by military necessity, and served primarily political aims. They inflicted enormous damage on the peaceable population.

Fulfilling the obligations entered into by agreement with its allies and aiming for a very speedy ending of the second world war, the Soviet government on 8 August 1945 declared that from 9 August 1945 the USSR would be in a state of war against [Japan], and associated itself with the 1945 Potsdam declaration... of the governments of the USA, Great Britain and China of 26 July 1945, which demanded the unconditional capitulation of [Japan] and foreshadowed the bases of its subsequent demilitarization and democratization. The attack by Soviet forces, smashing the Kwantung Army and liberating Manchuria, Northern Korea, Southern Sakhalin and the Kuril Islands, led to the rapid conclusion of the war in the Far East. On 2 September 1945 [Japan] signed the act of unconditional capitulation.

Though Japan had declared its surrender three days before the August 18 Soviet invasion of the Kuril Islands, the Soviet invasion of Manchuria was well underway, and so potentially creditable for playing a part in the initial declaration.

Still others have argued that war-weary Japan would likely have surrendered regardless because of a collapse of the economy; the lack of army, food, and industrial materials; threat of internal revolution; and the talk of surrender since earlier in the year. However, others find it unlikely and argue that Japan could likely have put up a spirited resistance.

The Japanese historian Sadao Asada argues that the ultimate decision to surrender was a personal decision by the emperor, who was influenced by the atomic bombings.

In his 2007 biography of Hirohito, Japanese historian Ikuhiko Hata wrote:

The author has made it a habit, when meeting with former members of the Imperial Army and Navy, to ask which had the greater impact at the time: the atomic bombs or the Soviet entry into the war? The responses run about 50-50, yet all agree that neither blow alone would have been sufficient; if they had not coincided, an end to the war in August 1945 would have been impossible.

Atomic diplomacy

A further argument, discussed under the rubric of "atomic diplomacy" and advanced in a 1965 book of that name by Gar Alperovitz, is that the bombings had as primary purpose to intimidate the Soviet Union and were the opening shots of the Cold War. Along those lines, some argue that the United States hoped to drop the bombs and receive surrender from Japan before a Soviet entry into the Pacific War. However, the Soviet Union, the United States, and the United Kingdom came to an agreement at the Yalta Conference on when the Soviet Union should join the war against Japan and on how the territory of Japan was to be divided at the end of the war.

Others argue that such considerations played little or no role, the United States being instead concerned with the surrender of Japan, and in fact, the United States desired and appreciated the Soviet entry into the Pacific War, as it hastened the surrender of Japan. In his memoirs, Truman wrote: "There were many reasons for my going to Potsdam, but the most urgent, to my mind, was to get from Stalin a personal reaffirmation of Russia's entry into the war against Japan, a matter which our military chiefs were most anxious to clinch. This I was able to get from Stalin in the very first days of the conference."

Campbell Craig and Fredrik Logevall argue the two bombs were dropped for different reasons:

Truman's disinclination to delay the second bombing brings the Soviet factor back into consideration. What the destruction of Nagasaki accomplished was Japan's immediate surrender, and for Truman this swift capitulation was crucial in order to preempt a Soviet military move into Asia.... In short, the first bomb was dropped as soon as it was ready, and for the reason the administration expressed: to hasten the end of the Pacific War. But in the case of the second bomb, timing was everything. In an important sense, the destruction of Nagasaki—not the bombing itself but Truman's refusal to delay it—was America's first act of the Cold War.

Public opinion

In the United States

The Pew Research Center conducted a 2015 survey showing that 56% of Americans supported the atomic bombings of Hiroshima and Nagasaki and 34% opposed. The study highlighted the impact of the respondents' generations, showing that support for the bombings was 70% among Americans 65 and older but only 47% for those between 18 and 29. Political leanings also impacted responses, according to the survey; support was measured at 74% for Republicans and 52% for Democrats. There are also differences in support and disapproval by ethnic groups. According to a CBS News survey, 49% of white Americans supported the atomic bombings, while only 24% of non-white Americans supported the bombings.

In a 2025 Pew Research Center survey conducted ahead of the 80th anniversary of the bombings, American views appeared more divided than ever: only 35% of respondents said the bombings were justified, while 31% said they were not justified, and 33% were unsure. The 2025 survey also revealed that older adults (65+) remained the most supportive age group (48%), while adults under 30 were more likely to say the bombings were unjustified (44%) than justified (27%).

American approval of the bombings has decreased substantially since 1945, when a Gallup poll showed 85% support while only 10% disapproved. Forty-five years later, in 1990, Gallup conducted another poll and found 53% support and 41% opposition. Another Gallup poll in 2005 echoed the findings of the 2015 Pew Research Center study by finding 57% support with 38% opposition. While the poll data from the Pew Research Center and Gallup show a stark drop in support for the bombings over the last half-century, Stanford political scientists have conducted research supporting their hypothesis that American public support for the use of nuclear force would be just as high today as in 1945 if a similar yet contemporary scenario presented itself.

In a 2017 study conducted by political scientists Scott D. Sagan and Benjamin A. Valentino, respondents were asked if they would support the use of atomic force in a hypothetical situation that kills 100,000 Iranian civilians versus an invasion that would result in the deaths of 20,000 American soldiers. The results showed that 59% of Americans would approve of a nuclear strike in such a situation. However, a 2010 Pew survey showed that 64% of Americans approved of Barack Obama's declaration that the US would abstain from the use of nuclear weapons against nations that did not have them.

In other countries

The atomic bombings are often discussed from the viewpoint that they reduced casualties among soldiers, but this reflects a U.S. perspective; in other countries, the issue is frequently debated from different viewpoints.

Japan

As the only country to have suffered atomic bombings, Japan maintains a strong social taboo against making jokes about nuclear weapons. In a 2015 survey, 79% of Japanese said the bombings could not be justified and 14% said they could.

A notable recent example occurred in 2023 with the release of the film Barbie, which premiered concurrently with Oppenheimer, a biographical drama about the creator of the atomic bomb. This led to the emergence of a viral "Barbenheimer" meme trend among American audiences, featuring images that combined Barbie's iconic style with imagery of mushroom clouds. The official U.S. Barbie movie account on social media responded positively to such memes, posting "It's going to be a summer to remember" (already deleted).

This reaction sparked backlash from the Japanese public and international media, with critics stating, for example, "In the US, people never make fun of the 9/11 attack or what Nazis did, but they can joke about the atomic bombings. I cannot express how saddened I am. This is regrettable." Others pointed out that the incident once again exposed the deeply self-serving standards of U.S.-led political correctness, which selectively enforces sensitivity while effectively tolerating racism against Asians. Amid growing criticism, Warner Bros., the distributor of the film, which had initially downplayed the issue, issued a formal apology.

Although it was the Japanese military that started the Pacific War, even those who were critical of the military did not necessarily support the atomic bombings. Shigeru Yoshida and Jiro Shirasu were both known for opposing the war and clashing with the military during the Pacific War. After World War II, they gained strong popularity among the Japanese public.

The GHQ pressured the Japanese side to translate their English-language draft of the new constitution into Japanese within just a few days. It is said that they used the word "atomic"—a taboo for the Japanese at the time—to intimidate them into speeding up the process, saying bluntly, "We have been enjoying your atomic sunshine." Upon hearing this, Yoshida was reportedly furious, stomping his foot and shouting, "What the hell was that?!" He sarcastically retorted, "GHQ stands for Go Home Quickly!"—a sentiment Jiro Shirasu is said to have agreed with.

In Japan, just before the end of the war, Masatomi Hatakeda, the governor of Niigata City with a population of 170,000, decided on a policy of "atomic bomb evacuation." Additionally, evacuation of civilians in response to air raids was promoted by civilian bureaucrats. Governor Akira Shimada of Okinawa is known for opposing the military in order to protect civilians during the Battle of Okinawa. As a result, while the military insisted on total national mobilization including civilians, the civilian officials aimed to protect civilians from the U.S. air raids, creating a clear conflict between the two. Consequently, in postwar Japan, there was a tendency to be critical of the U.S. air raids and atomic bombings, and the U.S. military was not viewed as liberators. At the same time, civilian officials who opposed the war and clashed with the military, as well as those who organized evacuations of civilians to protect them from U.S. air raids, were often respected.

Japanese journalist Soichiro Tahara once interviewed Henry Kissinger about the atomic bombings of Japan. He asked, "You dropped atomic bombs on Hiroshima and Nagasaki, killing a large number of completely innocent civilians. How does America intend to take responsibility for this?" Kissinger reportedly replied, "If we hadn't dropped the bombs on Hiroshima and Nagasaki, Japan would have launched a full-scale homeland battle. That battle would have caused the deaths of millions, perhaps over ten million Japanese people. By dropping the bombs, we significantly reduced that number, so in fact, Japan should be grateful to America."

European countries

In a 2016 survey, 41% of British respondents said the bombings were the wrong decision, while 28% said it was the right decision.

Alex Wellerstein, a nuclear historian at Stevens Institute of Technology, says that while the nations invaded by Japan were favor for the atomic bombings, Europeans generally have a cold view. Europeans are struck by the fact that the majority of Americans believe the atomic bombings of Hiroshima and Nagasaki were justified and morally right.

A 2025 international survey conducted across six Western countries revealed significant differences in public attitudes toward the moral justification of the atomic bombings of Hiroshima and Nagasaki. In European countries, a majority of respondents considered the bombings morally unjustified—81% in Germany, 78% in Italy, 75% in Spain, 57% in France, and 50% in the United Kingdom. In contrast, public opinion in the United States was more divided, with 38% saying the bombings were morally justified, 35% saying they were not, and 26% unsure. The results highlight a lasting divergence in views between Europe and the United States regarding the use of nuclear weapons in World War II.

Asian countries

In the Philippines, the atomic bombings of Hiroshima and Nagasaki are often seen as having contributed to the end of World War II and thus the end of Japanese occupation. However, there is also a critical perspective due to the country's history of American colonization. The Philippine-American War (1899–1902) and events like the Balangiga Massacre and General Jacob H. Smith's infamous order to "kill everyone over ten" foster a negative view of American imperialism. As a result, while some Filipinos view the U.S. as a liberator, others see it as an aggressor just like Japan, reflecting the complex legacy of American influence.

In South Korea, it is often suggested that the atomic bombings contributed to Korean independence. However, at the time, Korea was under Japanese colonial rule, and many Koreans had come to Japan as immigrants or wartime laborers. As a result, it is estimated that tens of thousands of Koreans were among the Hibakusha of the atomic bombings. This narrative of decolonization, however, often sidelined the actual Korean victims—those who were killed or exposed to radiation during the attacks. Korean hibakusha have expressed criticism toward both Japan and the United States. Jeon Wonsul, president of the Korean Atomic Bomb Victims Association, stated, "It was the United States that dropped the atomic bomb, and Japan that started the war. Seventy-eight years have passed, but neither the United States nor Japan has offered an apology or said anything about it." The differences in attitudes toward the atomic bombings were a barrier to understanding between South Koreans and Zainichi Koreans.

In Vietnam, due to its alignment with the Soviet Union during the Cold War, the official government view is that it was the Soviet Union's entry into the war—not the atomic bombings—that brought the Pacific War to an end. However, a few voices, such as that of Nguyễn Chí Thiện, argue that the atomic bombings were the decisive factor in Japan's surrender. On the other hand, the atomic bombings of Hiroshima and Nagasaki are also widely criticized. The Institute of Military Social Sciences and Humanities under Vietnam's Ministry of National Defense has published papers describing the use of Agent Orange during the Vietnam War as a form of chemical warfare, and discussing its brutality alongside that of the atomic bombings.

Countries in conflict with the U.S.

Sentiment is also very negative in countries that are in diplomatic conflict with the United States. In 1959, Che Guevara, when he visited Hiroshima, said, "America did a terrible thing. Aren't you Japanese angry about the atrocity that was perpetrated on you?" Cuban President Fidel Castro during a speech criticizing United States foreign policy said "We cannot ignore Hiroshima or Nagasaki, and the unnecessary use of Nuclear Weapons—a completely unnecessary use which, in any event, could have been used against military installations but instead fell on civilian populations of hundreds of thousands of inhabitants. It rang in the era of atomic terror in the world." Former Supreme Leader of Iran Ali Khamenei said, "The United States dropped one atomic bomb on the city of Hiroshima in August 1945, massacring 100,000 people in an instant. Such a hegemonic army as it is clearly shows that the U.S. is morally bankrupt, atheistic, and irreligious." In 2009, Venezuelan President Hugo Chávez stated at a joint press conference with Iranian President Mahmoud Ahmadinejad, "They're [the United States] the ones with the atomic bombs, and remember the Yankee imperialists dropped bombs on Hiroshima and Nagasaki". He also said that the United States should apologize for dropping atomic bombs on Japan at the end of World War II. On the 80th anniversary in 2025 of the atomic bombings of Hiroshima and Nagasaki, Nicaraguan Vice President Rosario Murillo condemned the attacks as crimes against humanity, noting that between 150,000 and 246,000 civilians were killed. She criticized those who still try to hide or obscure the identity of the perpetrators, emphasizing that Nicaragua has always clearly pointed them out. Murillo also drew a parallel between the bombings and the ongoing violence in Gaza, saying the same criminal and genocidal pattern continues today.

Negative impact on U.S. military and foreign policy

The French political and strategy scientist Frédéric Saint Clair pointed out that the atomic bombings of Hiroshima and Nagasaki were etched into American military strategy as a "successful experience," leading the United States to act on the mistaken assumption that "subduing the enemy by force" would be effective in later wars—such as the Vietnam War and the Iraq War—thereby causing long-term negative consequences.

The events of August 6, 9, and 10, 1945, support the thesis that American militarists have kept in mind—and have continued to revive over the decades. Yet there have been many counterexamples. The disaster of the Bay of Pigs in 1961. The resounding fiasco of the Vietnam War, from 1955 to 1975. The interminable war in Afghanistan, launched in the wake of the events of September 11, 2001. The failure of the Iraq War, which began in 2003, despite the "victory" of the U.S. and the fall of the dictator—if one considers the chaos that has reigned in the region ever since. And this is not an exhaustive list.

It was also the American historian of modern Japan, John Dower, who pointed out that the United States' positive framing of its occupation of Japan and the atomic bombings later had negative consequences. He argued that Japan likely would have surrendered even without a U.S. invasion — as long as the U.S. had accepted the continued existence of the emperor, which it ultimately did.

Dower also criticized the Bush administration for promoting Japan as a successful case of democratization in a non-Western context. He pointed out that this not only ignored the ongoing and often controversial debates within Japan about the occupation period, but also failed to recognize the vast differences between Japan and Iraq. Despite these differences, the administration tried to use Japan as a model case.

As an example, Dower noted that Japan had already undergone democratic developments, such as the enactment of the Meiji Constitution after the Meiji Restoration and the Taisho Democracy. He also emphasized Japan's geographical isolation as an island nation, its long history of shared identity, and the relative absence of deep societal divisions based on religion or ethnicity.

This trend continued into 2024, with Lindsey Graham arguing that since the United States dropped two atomic bombs on Japan at the end of World War II, Israel should also use all kinds of bombs in the Gaza Strip. Tim Walberg and Randy Fine also shared the same view and made similar remarks.

Influence for current international relations

The atomic bombings of Hiroshima and Nagasaki by the United States have frequently been discussed in international politics, often brought up in debates about the justification of war, criticism of the United States, and reasons for military expansion.

Russia

The fact that the U.S. is the only country to have dropped an atomic bomb on a city is an aspect that is used for diplomatic purposes. When Vladimir Putin annexed the Donetsk and Luhansk oblasts after invading Ukraine, he said the U.S. was the only country to have used nuclear weapons and set a "precedent". He also stated that neither the bombing of Germany nor the atomic bombing of Japan was militarily necessary; the purpose was to intimidate our country and the world. He wanted to use the atomic bombings of Hiroshima and Nagasaki as justification for the possible use of Russian nuclear weapons in the war in Ukraine.

However, at the G7 Hiroshima Summit in 2023, President Zelensky was invited and the "G7 Leaders' Hiroshima Vision on Nuclear Disarmament" was adopted. In both 2023 and 2024, representatives of Russia and Belarus were not invited to the Peace Ceremony in Hiroshima. Russian Ambassador to Japan Mikhail Galuzin called the response a "shameful measure" and said, "I have no idea which country committed the horrific civilian genocide of dropping the atomic bombs".

People's Republic of China

Politically China frequently criticized the U.S. for dropping atomic bombs on Hiroshima and Nagasaki. For example, on February 12, 1961, the People's Daily published a signature article titled "Between 'Hero' and 'Madman,'" condemning the act. In 1983, Hu Yaobang, then the top leader of the Chinese Communist Party, visited Japan, and one of his most significant stops was Nagasaki. The word "peace", written by Hu Yaobang, is still inscribed in Nagasaki's Peace Park. At the same time, some of its military leaders have stated that Japan tends to respect the strong in foreign relations, citing the atomic bombings by the United States, the invasion of Manchukuo by the Soviet Union, and the Tang Dynasty in the past, and China should therefore strengthen its military power.

On July 5, 2021, Japan's deputy prime minister Tarō Asō said that if the People's Liberation Army were to invade Taiwan, Japan should join the United States militarily. On July 11, a Chinese military affairs commentary channel on Xigua Video argued that if Japan intervenes, China should make an exception to its no-first-use nuclear policy and strike the country until it surrenders. It claims that due to Japan's unique experience, nuclear deterrence would be doubly effective. Xigua Video took down the clip, but it was later reposted by a municipal committee of the Chinese Communist Party in Baoji City.

Criticisms and discussions about Atomic Bomb Casualty Commission

Criticism and debate exist not only regarding the atomic bombings themselves but also concerning the Atomic Bomb Casualty Commission (ABCC), which conducted surveys on the aftermath of the bombings. The Atomic Bomb Casualty Commission (ABCC) was established in 1946 following a presidential directive from Harry S. Truman. The sole purpose of the organization was to conduct research on atomic bomb survivors because it was believed that "they would not be available again until a new world war occurred". Consequently, the organization studied the health of the hibakusha but did not provide them with any medical care. For this reason, the ABCC was criticized by the hibakusha as being experimental on human bodies.

After the atomic bombings, Japanese doctors wanted to understand and study the actual damage and conduct research to help treat the hibakusha. However, the GHQ did not allow Japanese researchers to study the current state of A-bomb damage. Regulations were particularly strict until 1946, resulting in a higher number of radiation-related deaths.

In one case, when a Zainichi Korean hibakusha fathered twins but died shortly after, the ABCC even attempted to recover the bodies of the deceased children. When hibakusha refused routine medical examinations, the ABCC threatened them with court-martial for war crimes. Furthermore, when hibakusha died, the ABCC would visit their homes in person to collect their bodies for autopsies. It is believed that at least 1,500 organs were sent to the Armed Forces Institute of Pathology in Washington, D.C.