 When Beria told Stalin about the Manhattan Project and its importance Stalin handpicked Molotov to be the man in charge of the Soviet atomic bomb project . However , under Molotov 's leadership the bomb , and the project itself , developed very slowly and Molotov was replaced by Beria in 1944 on the advice of Igor Kurchatov . When Harry S. Truman , the American president , told Stalin that the Americans had created a bomb never seen before , Stalin relayed the conversation to Molotov and told him to speed up development . On Stalin 's orders the Soviet government substantially increased investment in the project . 
