June 1945, McCormack returned to duty with the War Department General Staff as a member of the Policy Section of the Strategy and Policy Group, becoming the assistant section chief on 16 September 1945. He was then a staff officer with the Strategy and Policy Group from 16 February until 16 August 1946, when he became chief of the Politico-Military Survey Section of the Operations and Plans Division. For his service with the War Department General Staff, he was awarded an oak leaf cluster to his Legion of Merit on 8 April 1947. Cold War At this point, McCormack had become apprehensive about his career, but in early 1947 a new and exciting opportunity opened up. The Atomic Energy Act of 1946 had created the United States Atomic Energy Commission (AEC) to oversee research and development of nuclear power and nuclear weapons. The Act had created a statutory position inside the AEC called the Director of Military Applications, which the AEC commissioners envisaged as a staff post responsible for military planning and policy formulation. By law, the Director of Military Applications had to be a serving armed forces officer. The frontrunner for the post was the wartime commander of the Manhattan District, Brigadier General Kenneth Nichols. Indeed, Nichols was the War Department's only nominee. However, the AEC commissioners had different ideas. Nichols was seen as too closely identified with the wartime Manhattan Project; he had opinions at variance with the commissioners on whether the Director of Military Applications was a staff or a line position; and he had a strong disagreement with the commissioners over the vexing issue of which agency should hold custody of the nuclear weapons stockpile. Accordingly, the AEC commissioners decided to find another candidate. The AEC commissioners asked for Major General Lauris Norstad, the head of the Operations and Plans Division, but neither the Chief of Staff of the Army, General of the Army Dwight D. Eisenhower, nor the Secretary of War, Robert P. Patterson, was willing to release him. The commissioners then selected McCormack. The job came with a promotion to brigadier general. The commissioners got the kind of officer that they wanted. McCormack was willing to accept the post as a staff job, and took a pragmatic approach to the custody issue. Like most military officers, he was convinced that the men who had to use the nuclear weapons in battle needed to have