Anti-Vietnam Movement in the U.S. The antiwar movement against Vietnam in the US from 1965-1971 was the most significant movement of its kind in the nation's history. The United States first became directly involved in Vietnam in 1950 when President Harry Truman started to underwrite the costs of France's war against the Viet Minh. Later, the presidencies of Dwight Eisenhower and John F. Kennedy increased the US's political, economic, and military commitments steadily throughout the fifties and early sixties in the Indochina region. Prominent senators had already begun criticizing American involvement in Vietnam during the summer of 1964, which led to t