The significance of the Vietnam War in shaping U.S. foreign policy was profound, marking a shift toward a more cautious approach in international engagements. The war profoundly influenced American public opinion and led to widespread anti-war movements, creating a legacy of skepticism towards government authority and military interventions. The costly conflict prompted the U.S. to adopt the Vietnam Syndrome, a reluctance to engage in foreign military conflicts without clear objectives or public support. This war reshaped U.S. diplomacy, leading to a preference for detente with adversaries and a focus on multilateralism in foreign relations.