The American demonstration of its ultimate military superiority with the dropping of the atomic bombs on Hiroshima and Nagasaki created a sense of security that led both Washington and Ottawa to allocate low budgets for North American defense in the early postwar period. Security estimates did not project attacks upon the continent in the years following World War II, so the U.S. military saw this as an opportunity to emphasize military spending in areas of offensive capabilities.
The Soviet detonation of a nuclear device in late 1949, however, swiftly changed such views. American, and with that Canadian, national security assessments now estimated that a nuclear air attack by the Soviet Union on North American targets was possible. Ordered by President Truman in January 1950, the national security review that resulted in NSC-68 stated with respect to Soviet military capabilities that Moscow was in a position to "attack selected targets with atomic weapons, now including the likelihood of such attacks against targets in Alaska, Canada, and the United States." Heavily influenced by George F. Kennan's depictions of the Kremlin's inherent expansionist motives, NSC-68 sought to contain the communist threat through a "Rapid Build-up of Political, Economic, and Military Strength in the Free World." In light of Moscow's large standing armies and its increasing nuclear arsenal, NSC-68 called for a broad effort based on the further integration of nuclear arms but most importantly emphasized the expansion of U.S. conventional military capabilities (NSC-68).
The outbreak of the Korean War in the summer of 1950 further reinforced American views about the Soviets' hostile intentions and the need for the expansion of the North American air defense infrastructure. As a result, Washington set up a series of study groups that were instructed to investigate existing continental air defenses and related issues as well as make recommendations for improvements.