Perspective view of a mine at Taboshar, Tajikistan, from 1944. Taboshar was one of the few early sources of Soviet uranium, known since the 1920s and mined extensively for uranium since 1945. The acquisition of raw uranium was the key setter of the timetable of the Soviet bomb program. They had very few known sources of the ore at the end of World War II, and the United States and the United Kingdom had worked behind the scenes to attempt secure a monopoly on all other known world supplies. General Groves thought their access to uranium was so bad that it would take the Soviets 20 years to get a bomb — but it turned out that uranium is more plentiful than he realized, and concentrations that wouldn’t be economic to mine for the United States turned out to be just fine for Soviet slave labor.