 During President John F. Kennedy's term, while McNamara was Secretary of Defense, America's troops in South Vietnam increased from 900 to 16,000 advisers, who were not supposed to engage in combat but rather to train the Army of the Republic of Vietnam (ARVN).The Truman and Eisenhower administrations had committed the United States to support the French and native anti-Communist forces in Vietnam in resisting efforts by the Communists in the North to unify the country, though neither administration established actual combat forces in the war.The U.S. role—initially limited to financial support, military advice and covert intelligence gathering—expanded after 1954 when the French withdrew.