In late 1945, a hot debate began over whether the US should pass information to a body supervising world control of nuclear energy. Another aspect of American optimism regarding atomic energy in the late 1940s coalesced around the hope that world leaders would cooperate in the control of nuclear energy to strengthen the chance that Hiroshima and Nagasaki would never re-occur. By the time Churchill made his famous "Iron Curtain" speech in 1946, the Cold War was officially on. The chill of the Cold War permeated every aspect of American society. By 1939, after disempowering, imprisoning, or killing his political foes, abolishing all freedoms, and making a potent military the centerpiece of German society, the Nazi leader was poised to fulfill his vision of German dominance. In 1958, the two superpowers finally succumbed to the mounting evidence of danger and public outcry, and negotiated an agreement to halt all nuclear testing indefinitely.