The Mutual Defense Assistance Act was a United States Act of Congress signed by President Harry S. Truman on 6 October 1949. For U.S. foreign policy, it was the first U.S. military foreign aid legislation of the Cold War era, and initially to Europe. The Act followed Truman's signing of the Economic Cooperation Act, on April 3, 1948, which provided non-military, economic reconstruction and development aid to Europe.

Civil Air Transport (CAT) was a Nationalist Chinese airline, later owned by the U.S. Central Intelligence Agency (CIA), that supported United States covert operations throughout East and Southeast Asia. During the Cold War, missions consisted in assistance to "Free World" allies according to the Mutual Defense Assistance Act of 1949.