The United States provided aid to South Vietnam .
The United States was not directly involved until the Gulf of Tonkin Resolution , passed in reaction to a supposed North Vietnamese attack upon American destroyers , brought the U.S. into the war as a belligerent .
The United States provided aid to South Vietnam , but was not directly involved until the Gulf of Tonkin Resolution , passed in reaction to a supposed North Vietnamese attack upon American destroyers , brought the U.S. into the war as a belligerent .