The significance of the Cold War in shaping U.S. foreign policy lies in its pervasive influence on global relations and national security strategies. Spanning from the late 1940s to the early 1990s, the Cold War was characterized by political, military, and ideological rivalry with the Soviet Union. This rivalry prompted the U.S. to adopt a policy of containment to prevent the spread of communism, leading to military engagements in Korea and Vietnam, as well as forming alliances like NATO. The Cold War also spurred significant advancements in technology, military strategy, and diplomacy, fundamentally reshaping international relations and influencing U.S. domestic policies in countless ways.