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Communism was threatening free governments across the globe. Any sign of non-intervention from the United States might encourage revolutions elsewhere.
As the war dragged on, more and more Americans grew weary of mounting casualties and escalating costs. The small antiwar movement grew into an unstoppable force, pressuring American leaders to reconsider its commitment.
PEACE MOVEMENT leaders opposed the war on moral and economic grounds. The North Vietnamese, they argued, were fighting a patriotic war to rid themselves of foreign aggressors. Innocent Vietnamese peasants were being killed in the crossfire. American planes wrought environmental damage by dropping their defoliating chemicals.