The Krulak–Mendenhall mission was a fact-finding expedition dispatched by the Kennedy administration to South Vietnam in early September 1963. The stated purpose of the expedition was to investigate the progress of the war by the South Vietnamese regime and its US military advisers against the Viet Cong insurgency. The mission was led by Victor Krulak and Joseph Mendenhall. Krulak was a major general in the United States Marine Corps, while Mendenhall was a senior Foreign Service Officer experienced in dealing with Vietnamese affairs.

Roger Hilsman Jr. was an American soldier, government official, political scientist, and author. He saw action in the China-Burma-India Theater of World War II, first with Merrill's Marauders, getting wounded in combat, and then as a guerilla leader for the Office of Strategic Services. He later became an aide and adviser to President John F. Kennedy, and briefly to President Lyndon B. Johnson, in the U.S. State Department while he served as Director of the Bureau of Intelligence and Research in 1961 to 1963 and Assistant Secretary of State for Far Eastern Affairs in 1963 to 1964.