Final answer:
President Harry S. Truman signed the National Security Act of 1947 to overhaul the U.S. military and intelligence framework, establishing the NSC and CIA to counter the Soviet threat and streamline defense efforts during the early stages of the Cold War.
Step-by-step explanation:
Truman and the National Security Act
President Harry S. Truman created the National Security Act of 1947 to reorganize the United States' military and intelligence services in response to growing geopolitical tensions and security challenges, particularly those presented by the Soviet Union during the early Cold War era. The Act established the National Security Council (NSC) and the Central Intelligence Agency (CIA), which played crucial roles in shaping American foreign policy and intelligence practices. It also created a separate Department of the Air Force and later unified the different military branches under the Department of Defense, streamlining defense administration and preparing the country for potential conflicts.
The Act was significant because it centralized the security structure of the U.S. government, allowing for more coordinated and efficient defense and intelligence operations. Such restructuring was essential for containing the perceived spread of Communism, which Truman and his advisors deemed as the foremost security challenge. The CIA, specifically, expanded its role from intelligence gathering to covert operations, significantly influencing foreign governments during the Cold War.