Los Alamos Laboratory

Los Alamos Laboratory was a center of the Manhattan Project, the secret undertaking that produced the atomic bomb. Its importance emerges through a tension running from the laboratory’s strained, unfinished work to the weapon’s immense destructive power—and through the later discovery that secrets from Los Alamos had reached the Soviet Union.

A secret project

For a time, investigators examining government spending encountered unexplained expenditures for a project identified only as the Manhattan Project, larger even than the Canol Project. In June 1943, Harry S. Truman asked the Secretary of War about it. He was told that the development was exceptionally secret and important; by July, he had learned enough to understand its essential nature. These disclosures establish the atmosphere surrounding the work associated with Los Alamos: information was tightly controlled even within the government.

The scale of the project became starkly visible in a later briefing to Truman. A memorandum warned that, within four months, the United States would probably have completed a weapon capable of destroying a whole city. The United States and Britain had shared in its development, but only the United States could then produce it. The memorandum also warned that this advantage would not last and identified the Soviet Union as the nation most likely to develop production capability in the next few years.

Work under strain

In the weeks before the bomb’s use was decided, J. Robert Oppenheimer was described as exhausted and physically depleted. Work at Los Alamos was encountering problems: detonators were not firing as they should, and the project was falling behind schedule. Oppenheimer had contracted chickenpox, lost 30 pounds, and weighed 115 pounds despite being more than six feet tall. The account presents the laboratory’s work not as effortless scientific triumph but as a pressured undertaking beset by technical delays and personal strain.

Disagreement over the weapon

The laboratory’s work carried consequences that scientists understood differently. Leo Szilard, who opposed using atomic bombs against Japan on moral grounds, visited Oppenheimer while traveling back toward Chicago. According to Szilard’s recollection, Oppenheimer dismissed the bomb’s military usefulness, describing it as a tremendous explosion but not a weapon useful in war. This was Oppenheimer’s reported assessment, not evidence of a shared position among the laboratory’s scientists.

At the same time, Harry S. Truman was considering how to end the war with Japan. In his diary, he framed the choice as invasion or bombing and blockade, calling it his hardest decision to date; he did not mention the secret project in that entry. The contrast places Los Alamos’s work within a decision-making process in which the bomb’s development, potential military use, and the existing invasion plans did not always appear together in the same discussions.

Secrets reaching the Soviet Union

The laboratory’s secrecy proved vulnerable. Klaus Fuchs, a German-born physicist working at Los Alamos and a naturalized British citizen, had been supplying atomic secrets to the Soviet Union. The account says Soviet nuclear research had begun in 1942 and that information from Fuchs was regarded in Moscow as extremely valuable. When Truman told Joseph Stalin at the Potsdam Conference that the United States had a new weapon, Stalin’s uncurious response led American and British observers to think he had not understood its significance. In fact, he already knew more than they realized and urged Soviet officials to speed up their atomic work. Los Alamos therefore mattered not only as a site of bomb development but as a source of information that helped undermine the United States’ brief atomic advantage.