Battle For Okinawa: World War II     |     home
Atomic Bombs in WWII
"Tokyo rocks under the weight of our bombs...I want the entire world to know that this direction must and will remain - unchanged and unhampered, Our demand has been and it remains - unconditional surrender."
- President Truman, in his initial address to Congress, 16 April 1945.

Some facts behind the A bomb program
The development of the German V-1 and V-2 rocket weapons and the jet fighter plane in the last year of the War was too late to affect events, but indicates how dangerous at all times was the German capacity to invent engines of war. Up to the last moment, German morale could be boosted by mention of der Führer's promise
of secret weapons nearing readiness. America was taking notes and notice; their own secret weapons were nearing usable capability.

The Atom bomb had been worked at around the world, but was beyond the financial capabilites of private endeavor, but some of the best scientists had fled Germany for the west or died in allied bombardment of German rocket building facilities.

Albert Einstein, instigated by friendly physicists, wrote President Roosevelt in 1939 that the Nazis had the possibile capability to develope the A-Bomb and America should attend to it also. Einstein gave his concerns to better-connected colleagues to hand to Roosevelt. And FDR approved the Manhattan project and funded it with billions of dollars, all in secret. At the University of Chicago, the first nuclear chain reaction was accomplished.

At Alamogordo, New Mexico 1945, with the end of the War in Europe, the first A bomb was exploded, to the tune of attending scientists' exclamatory one-liners, and a couple of bombs were rendered ready to be dropped by B-29 bombers over the Japanese homeland.

In late April 1945, just one week after Truman reiterated what had been Roosevelt's policy of unconditional surrender, an intelligence report prepared for the Joint Chiefs of Staff warned that unconditional surrender could not be forced upon the Japanese before the middle or latter part of 1946 without a land campaign on the Japanese home islands.

Therefore, in April 1945, at the height of the Luzon and Okinawa campaigns, the Joint Chiefs of Staff instructed Admiral Nimitz and General MacArthur to make plans and preparations for an attack on Japan. Admiral King opposed any landing in Japan; he was convinced that the Japanese Army had great advantages on their home islands, and only consented to the invasion after Admiral Nimitz recommended in favor of it.

Operation Downfall

On 25 May 1945, the JCS issued a directive to begin formal planning for the campaign, code-named "Operation Downfall," which was to force Japan's unconditional surrender. Operation Downfall was divided into two major operations, Operation Olympic, the invasion of the island of Kyushu to be executed in the fall of 1945, and Operation Coronet, the invasion of Honshu, scheduled for the spring of 1946.

Meanwhile A shipment of weapons-quality uranium was discovered on a surrendered German submarine on its way to Japan: one more bit of hard evidence that, had they contrived the Bomb first, the Germans and Japanese would have exploded it upon Allied centers.

Aboard the U-234 Cargo U-boat bound for Japan when war ended was the cargo surrendered to U.S. authorities at sea carrying a total cargo of 260 tons, including uranium oxide ore, mercury, and the component parts for an Me 262 jet fighter. 234 Surrendered to destroyer escort USS Sutton east of the Flemish Cap, 14 May 1945, after two Japanese passengers committed suicide. Other passengers bound for Japan included several Luftwaffe officers and technical specialists intended to improve Japanese aircraft defenses. (The U.S. Navy used U-234 for experimental trials and then sank her off Cape Cod, November 1946)

In the western Central Pacific, the V Amphibious Corps, comprised of the Third, Fourth and Fifth Marine Divisions, assaulted Iwo Jima on 16 February 1945. The island was declared secure by the end of March and the three Marine divisions withdrew to their training bases in the Marianas and Hawaii. The third campaign identified by the JCS in its October 1944 directive began on 1 April 1945, when the Tenth Army comprised of seven divisions assaulted Okinawa. The island was not secured until three months later, on June 21. The ferocity of the Japanese defenders on Iwo Jima and Okinawa convinced American policymakers that Japan would not surrender unconditionally until she was decisively defeated at home.

General Simon Bolivar Buckner (killed on Okinawa) called this style of War; 'Prairie Dog Warfare'.

On 18 June 1945, President Truman held a Japanese strategy meeting at the White House. At this meeting he was briefed by the Joint Chiefs of Staff on the elements of Operation Downfall. Truman's primary concern was on the number of casualties and whether an invasion of the home islands was necessary. General Marshall gave Truman an estimate of approximately 40,000 U.S. casualties for Operation Olympic. After hours of discussion, Truman approved further planning for Olympic, with an execution date of 1 November 1945. Operation Coronet, if needed, would be conducted in March 1946.

Since the term "D-Day" had become synonymous with the European Theater of operations landing at Normandy on 6 June 1944, "X-Day" was designated as the term for the day of the landing on Kyushu.

X-Day Invasion of Japan

"Victory was never in doubt. Its cost was...What was in doubt, in all our minds, was whether there would be any of us left to dedicate our cemetery at the end, or whether the last Marine would die knocking out the last Japanese gun and gunner..."

- Major General Graves B. Erskine, Commanding General, 3rd Marine Division

The initial assault would be conducted by eleven US Army infantry divisions and three Marine divisions, divided into four corps under the command of General Walter Krueger's Sixth Army: I Corps consisted of the Army's 25th, 33rd, and 41st infantry divisions; XI Corps, the Army's Americal and 43rd infantry divisions and the 1st Cavalry division; IX Corps, the reserve, the Army's 81st and 98th infantry divisions; and the V Amphibious Corps, the Second, Third, and Fifth Marine divisions. The number of ground forces to be landed in the first four days of the assault would total approximately 436,486. Follow-up forces would number 356,902. With air support personnel of 22,160, the numbers topped 800,000 for Operation Olympic. Should it be found that the fourteen divisions allotted to the Sixth Army were insufficient to capture and hold southern Kyushu, that army would be reinforced at the rate of three divisions a month from X+30 by the units earmarked for Coronet.

Thousands of land based fighters and bombers of the Far East Air Forces would provide air support for Olympic. The Far East Air Forces, under the command of General George C. Kenney, belonged to MacArthur and included the Fifth, Seventh and Thirteenth Air Forces. Also providing air support were the Fleet Air Wings based on the carriers, and the 1st, 2nd, 3rd, and 4th Marine Aircraft Wings (MAW) which were mostly land based. The MAWs would provide support in the amphibious phase under the control of Admiral Spruance's Fifth Fleet. Once established ashore on Kyushu the Marine Aircraft Wings would fall under the control of the Far East Air Forces.  Also included in the operation were the strategic bombers of the Twentieth Air Force, and the 20th and 21st Bomber Commands. The thousands of B-29s from the U.S. Army Strategic Air Force in the Pacific would be conducting strategic bombing of Japanese cities.

"We must be prepared to accept heavy casualties whenever we invade Japan. Our previous success against ill-fed and poorly supplied units, cut down by our overpowering naval and air action, should not be used as the sole basis of estimating the type of resistance we will meet in the Japanese homeland where the enemy lines of communication will be short and the enemy supplies more adequate."
- Admiral Chester Nimitz, CINCPAC, in a memo to Admiral King, CNO, June 1945

During the early part of 1945, as the Joint Chiefs of Staff discussed plans to force the unconditional surrender of Japan, General MacArthur's staff in Australia undertook intelligence studies to assess Japanese defensive capabilities remaining in the home islands. The second intelligence estimate to be published was much more detailed and specific in regard to the location of Operation Olympic. The USAFPAC G-2 Estimate of the Enemy Situation With Respect to an Operation Against Southern Kyushu in November 1945 was issued on 25 April 1945.  On 29 July 1945, the USAFPAC G-2 issued an amendment to the 25 April intelligence estimate.

The conclusions of the 29 July intelligence estimate were:

- The rate and probable continuity of Japanese reinforcements into the Kyushu area are changing the tactical and strategic situation sharply.... we are engaged in a race against time by which the ratio of attack-effort vis-a-vis defense capacity is perilously balanced.

- The Japanese have correctly estimated southern Kyushu as a probable invasion objective, and have hastened their preparations to defend it.

- Japanese strength in southern Kyushu has grown to an estimated 206,000 troops. 7 divisions and 2 to 3 independent brigades, plus Naval, Air-Ground, and Base and Service troops.

- Unless the use of these (supply) routes is restricted by air and/or naval action ... enemy forces in southern Kyushu may be still further augmented until our planned local superiority is overcome, and the Japanese will enjoy complete freedom of action in organizing the area and in completing their preparations for defense.

This new estimate warned that if the Japanese troop deployments into Kyushu were not checked then the U.S. attack ratio may become one (1) to one (1).  The figure given to Truman at the outset based on his planning called for a 3 to 1 advantage to the American invasion forces.  

The suspected casualty figures were growning in mutiples of tens of thousands by the time the first A-Bomb was exploded in New Mexico.  One of the impacts that this estimate had was in the mind of General Marshall, for he contemplated the possibility of using the newly developed atomic bomb against Japanese forces on Kyushu in support of the invasion instead of against Japanese cities. Japan surrendered before there were any formal revisions to the Olympic plan or new casualty estimates were made using this revised estimate of Japanese strength.

The U.S. Sixth Army provided the intelligence estimates utilized by the V Amphibious Corps for their initial planning. These estimates were basically derived from the same intelligence used by the USAFPAC estimates addressed above. But, with grave exceptions.

Sixth Army came to different conclusions as to the capabilities and intentions of the Japanese forces. Sixth Army assumed that the Japanese had a very high degree of organization of the ground chosen for defense.

The USAFPAC estimates indeed were flawed. And the Sixth Army Intelligence proved correct.

In a major disagreement with the USAFPAC estimate, the Sixth Army assessed that there were 5,000 enemy combat planes of all types within range of intervention. In addition, an estimated 4,000 - 5,000 training planes could be used for kamikaze attacks.

The Sixth Army also believed that the Japanese would fight the decisive battle on Kyushu, and commit all of their aircraft, primarily in kamikaze attacks. Upwards of 10,000 aircraft would be available to the Japanese to conduct an all-out suicide air offensive against the transport ships and landing craft. These attacks would be strengthened by the probable widespread use of the suicide-piloted rocket plane (BAKA), which was modeled after the German V-1 rocket bomb.

USAFPAC estimates said that Japans airforce was limited in numbers and capabilities. 2,000 would be first line aircraft, while the remainder would be training planes or obsolete models. It was expected that an intense and violent air reaction would occur prior to landing, and probably consist largely of kamikaze attacks.

The attacks would include both massed air attacks, and frequent small sorties. However, it was assessed that no more than 500 to 800 aircraft would be sacrificed in attempts to prevent the Allied landing, therefore this threat would be manageable by the massive Allied naval and air invasion force. There was the belief that the Japanese were going to save the preponderance of their aircraft for the decisive battle on the Tokyo Plain, which would come in the spring of 1946.

The later capture of the Japanese plans proved that USAFPAC's strategy would have led to disaster.

The U.S. intelligence estimates of July 1945 were alarming to Olympic planners.

They warned that the build-up of Japanese forces in southern Kyushu was reducing the U.S. attack force ratio of 3:1 to 1:1. In fact, the Japanese by this time had surpassed the 1:1 ratio and actually outnumbered the American invasion force.

In July 1945, the U.S. intelligence estimates were underestimating Japanese strength on Kyushu by about 36 percent!

To make matters worse, General MacArthur, based on previous operations in the Pacific, believed that U.S. intelligence typically overestimated Japanese strength.

MacArthur downplayed his own staff's casualty estimates and told General Marshall that he "regarded the operation (Olympic) as the most economical one in effort and lives that is possible."

Admiral William Leahy estimated American casualties at 250,000.

General Charles Willoughby; MacArthurs own Chief of Intelligence estimated American casualties by the Fall of 1946; would be 1 million men; and Willoughby's Intelligence staff considered this to be a conservative estimate.

The underestimation of Japanese forces resulted from the continuous movement of Japanese forces into Kyushu throughout the spring and early summer of 1945.

At the strategic level, there was an incomplete intelligence picture based on faulty analysis.

MacArthur and the Joint Chiefs of Staff believed that the Japanese would not commit all of their resources in the battle for Kyushu; they assumed that the Japanese would husband their assets, especially aircraft, for the battle for Tokyo.

They failed to assess the Japanese' intention to fight a decisive final battle on Kyushu.

There was also a lack of understanding about the operational situation on Kyushu. In a Memorandum for the President, Details of the Campaign Against Japan, dated 15 June 1945, the Joint War Plans Committee wrote,

"The extent of the objective area gives us the opportunity to effect surprises at the points of landing and, once ashore, to profit by our superiority in mobility and mechanized power through maneuver."

This statement was used in an attempt to differentiate Olympic and Coronet from the bloody island battles in the Pacific.

However, the statement could not have been further from reality!

The Japanese had determined the exact location and time of the invasion, and certainly the terrain would have restricted the mobility and maneuver capability of the U.S. forces.

The major failure of intelligence concerned the Japanese capability for suicide attacks.

The Sixth Army report was the only correct assessment of the facts.  MacArthur and staff were wrong.

In spite of countermeasures, the suicide attacks directed against the U.S. task forces and transport areas would unquestionably have been serious and would have caused severe losses.

The kamikaze attacks against the U.S. fleet at Okinawa came after the aircraft flew more than 500 miles over open ocean. Many inexperienced pilots lost their way and never reached the American fleet. This great distance also allowed the fleet to receive early warning from picket ships and scramble fighters to engage the kamikazes. Bad weather in the target area also hampered the kamikaze pilots from acquiring their targets. With all of these difficulties, the Japanese ratio of planes launched to planes successfully striking their targets was 1 in 9.

The Japanese flew 1,840 "special-attack" planes during the battle for Okinawa. A ratio of 1 in 9 would equate to approximately 202 planes striking their targets.  The U.S. Navy reported 192 ships hit by kamikaze planes during the battle of Okinawa; of these, 15 were sunk.

Although the damage inflicted by the Kamikaze planes was superficial, they managed to kill 12,300 American servicemen and wound 36,400.

 For the defense of Kyushu the Japanese were to employ upwards of 10,000 kamikaze planes.

Although the Japanese staff planned for a hit ratio of 1 in 9, many believed that they would be far more successful. The special attack aircraft would have to fly less than 100 miles to their target with almost the entire distance spent over land masked by terrain. The U.S. fleet would have very little warning time to intercept the aircraft. Anchored troop transports, just off the coast, would be easy targets as they unloaded their cargo.

It is highly probable that the Japanese suicide attack hit ratio would have been higher, probably closer to 1 in 6 or 1 in 7. At these ratios, 1,400 to 1,600 kamikaze aircraft would have hit American ships. With their targets being transports, the casualty rate per hit would have been higher than at Okinawa where destroyers were the primary target.

In addition to the kamikaze aircraft, the U.S. fleet also would have had to deal with all of the Japanese Navy's special attack boats and midget submarines. Even if the suicide attacks were only marginally successful, the U.S. attack ratio would have eroded still farther. If the Japanese did succeed in delivering 1,500 hits against the transports, the mythical "Divine Wind" may well have blown again, turning away another invasion fleet.

On 18 July 1945, the Joint War Plans Committee issued another Memorandum for the President to assist Truman in preparing for the Potsdam Conference.  This memorandum again highlights the misunderstanding of the situation on Kyushu at the strategic level.  It claimed;

"the nature of the objective area in Kyushu gives maneuver room for land and sea operations. For these and other reasons it is probable that the ground cost in ground force casualties for the first 30 days of the Kyushu operation will be on the order of that for Luzon. Naval casualties will probably be at about the same rate as for Okinawa."

With the casualty ratios of those battles applied to Operation Olympic, the estimate for U.S. casualties would have been 94,000 killed and 234,000 wounded. The total casualty estimate of 328,000 equates to 57 percent of the U.S. ground forces slated for Olympic. On the Satsuma Peninsula, the V Amphibious Corps casualty estimate would have been 13,000 killed and 34,000 wounded, or approximately 54 percent of the Marine force. This casualty estimate for VAC is made without any additional Japanese forces moving into the 40th Army's zone. Add to these estimates the results of kamikaze attacks against transports, and the battle for Kyushu would have been devastating to the American people.

Many historians use the casualty estimate that was briefed to Truman in June 1945 to claim that the projected low casualty rate of 25,000 dead did not justify the use of the atomic bomb.

However, those casualty estimates were based on an April 1945 estimate of Japanese force strength of around 229,000.

By July 1945, that force had almost tripled to 657,000. With this sizable ground force supported by the special attack forces, it is easy to reach a total casualty figure of close to 500,000 Americans.

This is the same number used by Truman in later accounts in his diary to justify the use of the atomic bomb.

In addition to U.S. casualties, the Japanese on Kyushu would likely have suffered upwards of 2,000,000 military and civilian casualties.

These projected figures for Kyushu far exceed the casualties inflicted by the atomic bombs dropped on Hiroshima and Nagasaki, which ended the War with Japan.

General MacArthur was determined to lead the largest amphibious operation in history and General Marshall was willing to support MacArthur in this endeavor. Concerned about high casualties, President Truman had little enthusiasm for a ground invasion of the Japanese home islands.

It was General Marshall that downplayed the projected casualty figures and influenced Truman to approve the operation.

When intelligence estimates showed a Japanese defensive buildup, MacArthur all but ignored them, while Marshall contemplated the use of the atomic bomb in a tactical role.

If Operation Olympic had been executed, as planned, on 1 November 1945, it would have been the largest bloodbath in American history.

Although American forces had superior fire power and were better trained and equipped than the Japanese soldier, the close-in, fanatical combat between infantrymen would have been devastating to both sides.

It is important to note that American battle deaths for the entire war numbered approximately 292,000, with another 671,000 wounded.

Had not the Japanese surrendered after the dropping of the second atomic bomb on Nagasaki, Operation Olympic would most likely have been conducted in order to bring about Japan's unconditional surrender.

However, by the invasion date of 1 November 1945, intelligence would have accurately identified the true nature of the Japanese defensive capability on Kyushu.

New casualty estimates based on this intelligence, would likely have influenced President Truman to use the atomic bomb as a tactical weapon against the beach defenses on Kyushu. Although probably a successful tactic to defeat the Japanese on Kyushu, historian Edward Drea points out the dreadful results of such use of the atomic bomb:

"...American GIs and Marines who would have landed on radioactive beaches - another hell, that of radiation poisoning, might well have been in store. In 1945 no one really grasped the implications of radioactive fallout, and the hellish effects would undoubtedly have persisted for decades after the explosions."

Germany -- Atomic Bomb

Dec 18, 1938 Otto Hahn splits the uranium atom, releasing energy. Although top officials were invited to an atomic weapons session, the agenda described the presentation as of a technical nature and lower level individuals were assigned to attend. Little interest developed. Heavy water was recognized as a requirement. The activities to destroy the only facilities in Europe at that time, in Norway, are well documented on the commando raid, Feb 28, 1943, the bombing raid, Nov 16, 1943, and the sabotage sinking of the ferry in Jan, 1944. However, Germany had pretty well given up on the bomb by mid-1943 although work continued at
Haigerloch until the end.

Boris Pash, head of security for the Manhattan Project, and scientist Samuel Goudsmit followed the lead tanks into Paris and into Germany, looking for the German nuclear laboratory, which they found in Strasbourg. This was called Operation Alsos (Greek for "Groves"). Peter Goodchild in his book *J. Robert Oppenheimer, Shatterer of Worlds,* p. 110 said:

"Very soon a picture of the Germans' progress began to emerge. They revealed that Hitler had been told of the possibilities of a nuclear weapon in 1942 and that there had been a whole series of uranium pile experiments. But the crucial facts were that even as late as August 1944 the experiments were still at an early stage. The Germans had neither the certain information that an explosive chain reaction was possible, nor did they have the material or the mechanism to make their bomb. It was apparent that the project had moved forward hardly at all since 1942. There were one or two people in Washington who, when they read Goudsmit's final report, suspected that the information had come too easily, but most people believed it."

When the Allies found the German atomic bomb laboratory, they were amazed that it was just a small concrete reactor in a cave, too small to go critical. Yet they went to considerable trouble in a top secret program to grab these scientists because they might be useful in defeating Japan.  Tom Agoston in *Blunder!* says (p. 38) that "Unknown to Allied scientists, the Germans had been able to build up a sizeable stockpile of U-235 and had held up to two tons, as well as two tons of heavy water."

William Stevenson, in *A Man Called Intrepid,* says "The Germans had the man [Heisenberg] whose theoretical work was the basis of the bomb" (p. 456) and "In the military field, the view prevailed in 1939 that the country with the greatest chance of bringing together the pieces was Germany."

The German laboratory was captured on April 21, 1945, then three months later on July 16 a bomb was tested at Alamogordo, New Mexico. Then on August 6, 1945, one was dropped on Hiroshima, and August 9 on Nagasaki.  Pash and Goudsmit in Operation Alsos captured several tons of uranium and "it was shipped to Britain and then the United States, transformed into uranium hexaflouride gas for isotope separation at Oak Ridge, Tennessee, and finally in the form of U-235 used to destroy Hiroshima." (*Heisenberg's War,* p. 362.)

There is evidence to support the theory that Germany actually built the Atomic Bombs used against Japan. In Phoenix Journal #18 (*Blood And Ashes*), speaking of the Manhattan Project, "Of course, they utilized the German production urn and, actually, the bomb used on Japan was constructed in Germany" (p. 159).

It is well known that the atomic bomb was a German idea; they had the best scientists, they had a proven ability to develop advanced weapons, they had plenty of raw material.  Most classified files from World War II have been routinely declassified under the provisions of the U.S. Freedom of Information Act. Tom Agoston (*Blunder!,* p. 124) said of the Alsos information, "The files continued to be suppressed and remain under lock and key in Washington, well beyond the thirty-year rule. The motive for this remains a four-decade mystery."

"The stakes in the search for the scientific expertise of Germany were high. The single most important American strike force, for example, was the Alsos raiding team, which targeted Axis atomic research, uranium stockpiles, and nuclear scientists, as well as Nazi chemical and biological warfare research. The commander of this assignment was U.S. Army Colonel Boris Pash, who had previously been security chief of the Manhattan Project - the United States' atomic bomb development program - and who later played an important role in highly secret U.S. covert action programs. Pash succeeded brilliantly in his mission, seizing top German scientists and more than 70,000 tons of Axis uranium ore and radium products. The uranium taken during these raids was eventually shipped to the United States and incorporated in U.S. atomic weapons." (Simpson, Christopher, *Blowback,* Collier Books, New York, 1988, p. 26.)

Colonel Pash is one of the few remaining originals of U.S. intelligence, and his experience in 'fighting the communists' goes back to the 1917 Russian Revolution. His success against the German Atomic program is well known.
Japan - January 1943 -- Atomic Bomb

In the fall of 1940, the Japanese army concluded that constructing an atomic bomb was indeed feasible. The Institute of Physical and Chemical Research, or Rikken, was assigned the project under the direction of Yoshio Nishina. The Japanese Navy was also diligently working to create its own "superbomb" under a project was dubbed F-Go, headed by Bunsaku Arakatsu at the end of World War II.

The F-Go program [or No. F, for fission] began at Kyoto in 1942. However, the military commitment wasn't backed with adequate resources, and the Japanese effort to an atomic bomb had made little progress by the end of the war.

Dr Hideki Yukawa was awarded the Nobel Price in physics in 1949 for his extensive work with the atom begun in 1941. An atomic bomb project as launched by Prime Minister Hideki Tojo in January, 1943. Former colonel Toranosuke Kawashina was in charge. Design considerations were promising. All chance of success was destroyed when a German submarine carrying two tons of uranium was captured as it approached Japan.

Although the allied atomic bomb was developed from a threat by Germany, it was not completed until after VE day. It was used to avoid the expected 500,000 to one million US casualties from the invasion of the Japanese main islands against an army of almost three million men. Kamikaze boats and planes were being stockpiled. In addition, the public was being issued weapons. Two to five million Japanese casualties were anticipated.

It can be argued the atomic bomb saved Japanese civilian and military, as well as US lives. The sudden end certainly saved the lives of thousands of POWs and slave laborers scheduled for assassination upon invasion.

Japan's nuclear efforts were disrupted in April 1945 when a B-29 raid damaged Nishina's thermal diffusion separation apparatus. Some reports claim the Japanese subsequently moved their atomic operations Konan [Hungnam, now part of North Korea]. The Japanese may have used this facility for making small quantities of heavy water. The Japanese plant was captured by Soviet troops at war's end, and some reports claim that the output of the Hungnam plant was collected every other month by Soviet submarines.  

There are indications that Japan had a more sizable program than is commonly understood, and that there was close cooperation among the Axis powers, including a secretive exchange of war materiel. The German submarine U-234, which surrendered to US forces in May 1945, was found to be carrying 560 kilograms of Uranium oxide destined for Japan's own atomic program. The oxide contained about 3.5 kilograms of the isotope U-235, which would have been about a fifth of the total U-235 needed to make one bomb. After Japan surrendered on 15 August 1945, the occupying US Army found five Japanese cyclotrons, which could be used to separate fissionable material from ordinary uranium. The Americans smashed the cyclotrons and dumped them into Tokyo Harbor.