History of the United States 6–3 decision in Korematsu v. United States Supreme Court case. Research and development took flight as well, best seen in the Manhattan Project, a secret effort to harness nuclear fission to produce highly destructive atomic bombs. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs. The first nuclear device ever detonated was an implosion-type bomb at the Trinity test, conducted at New Mexico's Alamogordo Bombing and Gunnery Range on
Soviet atomic bomb project research programs. In April 1942, Flyorov directed two classified letters to Stalin, warning him of the consequences of the development of atomic weapons: "...the results will be so overriding [that] it won't be necessary to determine who is to blame for the fact that this work has been neglected in our country." The second letter, by Flyorov and Konstantin Petrzhak, highly emphasized the importance of a "uranium bomb": "it is essential to manufacture a uranium bomb without a delay." Upon reading the Flyorov letters, Stalin immediately pulled Russian physicists from their respective military services and authorized an atomic bomb project,