Isolationism, World War II, and Cold War/Vietnam War policies shaped US foreign policy over time.
Isolationism: The policy of avoiding entanglement in foreign affairs, seen in the period between World War I and World War II.
World War II: Catalyzed a shift in U.S. foreign policy towards international involvement, marking a departure from isolationism.
Cold War and Vietnam War: Guided by policies such as containment to limit Soviet influence and the use of military force as seen in Vietnam.
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