The U.S. military buildup in Vietnam begins.
Trade embargo is imposed on North Vietnam in response to attacks from the North on South Vietnam.
Pentagon says North Vietnamese torpedo boats attack the U.S. destroyer Maddox in the Gulf of Tonkin. Congress approves the Gulf of Tonkin Resolution allowing the president to take any necessary measures to repel further attacks. Number of U.S. troops in Vietnam grows from 60,000 to 543,000. The Tet Offensive. Communist forces launch attacks on Hue and other major cities, towns and military bases throughout South Vietnam.