Published Dec. 31, 1995|Updated Oct. 5, 2005
The Nazi submarine U-234, which surrendered to U.S. forces in May 1945, was found to be carrying a surprisingly diverse cargo bound for Tokyo as part of a secretive exchange of war materiel between Hitler and Hirohito.
The payload represented the pride of German technology and included parts and blueprints for proximity fuses, antiaircraft shells, jet planes and chemical rockets.
But nothing the U-234 concealed in its warrens was more surprising than 10 containers filled with 1,200 pounds of uranium oxide, a basic material of atomic bombs. Up to then, the Allies suspected that both Nazi Germany and imperial Japan had nuclear programs but considered them rudimentary and isolated.
Historians have quietly puzzled over that uranium shipment for years, wondering, among other things, what the U.S. military did with it. Little headway was made because of federal secrecy.
Now, however, a former official of the Manhattan Project, John Lansdale Jr., says that the uranium went into the mix of raw materials used for making the world's first atom bombs. At the time he was an Army lieutenant colonel for intelligence and security for the atom bomb project. One of his main jobs was tracking uranium.
Lansdale's assertion in an interview raises the possibility that the American weapons that leveled the Japanese cities of Hiroshima and Nagasaki contained at least some nuclear material originally destined for Japan's own atomic program and perhaps for attacks on the United States.
If confirmed, that twist of history could add a layer to the already complex debate over whether the United States had any moral justification for using its atom bombs against Japan.
A pivotal question that surrounds the episode is whether the three months between the U-234's surrender in May 1945 and the dropping of the U.S. bombs in August 1945 left the Manhattan Project's bomb builders enough time to incorporate the captured uranium.
Another is whether President Harry Truman, who authorized the atomic bombing of Japan, knew of the U-234's radioactive cargo.
At least a dozen historians, journalists and nuclear experts around the world are now at work on this and related mysteries surrounding the U-234, going through newly declassified documents and interviewing aging former members of the German and Japanese militaries and participants in the Manhattan Project.
"There's no question they were hurting for uranium," Stanley Goldberg, a science historian in Washington who is writing a book on the Manhattan Project, said of the U.S. bomb venture. "They scraped the bottom of the barrel. They came to within an inch of not having enough material for a uranium bomb."
As to whether the weapons used any of the U-234's uranium, Goldberg, like several historians and nuclear experts, said that he was unconvinced but intrigued.
Even if none of the submarine's cargo went into the explosive mix, some experts hold, the U-234 episode is important to explore for what it reveals about the Japanese atom bomb program, which has long been clouded in ambiguity.
Peter Zimmerman, a physicist who has studied the issue and advises the defense department, said, "Where it becomes very significant is if it helps demonstrate that the Japanese had a sizable program and that there was close cooperation among the Axis powers."
The U-234 left the German port of Kiel on March 25, 1945, bound for Japan on a voyage around the horn of Africa. After Hitler's death a month later, the submarine surrendered to U.S. forces in the North Atlantic and was taken to the U.S. submarine base at Portsmouth, N.H.
In secrecy the Navy took careful inventory of the submarine's crew and cargo, recording the details in an exhaustive manifest that today is in a public file at the Navy's Operational Archives at its Historical Center in Washington.
The manifest says that the uranium came in 10 cases, weighed 560 kilograms and was transported from Germany as an oxide, which is a handy industrial form refined from raw uranium ore. Kathy Lloyd, an archivist at the center, said that the Navy had "no paper trail" on where the shipment went after the inventory.
Zimmerman said that amount of uranium oxide would have contained about 3.5-kilograms of the isotope U-235, which is the critical one for making bombs. That 3.5-kilograms, he added, would have been about a fifth of the total U-235 needed to make one bomb.
Lansdale, the former official of the Manhattan Project, displayed no doubts in the interview about the fate of the U-234's shipment.
"It went to the Manhattan District," he said without hesitation. "It certainly went into the Manhattan District supply of uranium."
Lansdale added that he remembered no details of the uranium's destination in the sprawling bomb-making complex and had no opinion on whether it helped make up the material for the first atomic bomb used in war.
In theory the uranium might have helped fuel the uranium bomb that leveled Hiroshima or the plutonium bomb that was dropped on Nagasaki. In a kind of modern alchemy, plutonium is made by irradiating uranium in a nuclear reactor, turning it from one element into another.
Vilma Hunt, a nuclear expert working on a book about uranium used in the war, has researched the fate of the U-234's shipment for years. She said she had concluded that it went into the Manhattan Project's mix, not based on any positive evidence she had been able to unearth but simply because of the project's great need for weapons material.
"At that time there was a limited amount of uranium oxide available," she said. "We needed it."
Based on the comments of Lansdale, she added: "You could go as far as saying it was in the stream and would have had a high likelihood that it went into one of the first three bombs. That would have been pushing the system, but that's what they were doing."
The world's first atomic bomb was detonated in the New Mexico desert on July 16, 1945, as a test. Hiroshima was bombed on Aug. 6 and Nagasaki on Aug. 9.
Skip Gosling is chief historian of the federal department of energy, which is the successor agency to the Manhattan Project and is the federal government's authority on making nuclear arms.
"My guess is that none of it got in" the atomic bomb that was dropped on Hiroshima, Gosling said. "But I wouldn't bet my farm on that."
