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 and British scientists, Russian physicist Georgy Flyorov suspected that the Allied powers had secretly been developing a "superweapon" since 1939. Flyorov wrote a letter to Stalin urging him to start this program in 1942. Initial efforts were slowed due to the German invasion of the Soviet Union and remained largely composed of the intelligence knowledge gained from the Soviet spy rings working in the U.S. Manhattan Project. After Stalin learned of the atomic bombings of Hiroshima and Nagasaki that ended the Pacific War in 1945, the program was pursued aggressively and accelerated through effective intelligence gathering about the German nuclear