You can start the clock under Truman, since we financed the French war with cash subsidies and arms.<quoted text>
Actually, Vietnam started with President Eisenhower, who took the war over when the North Vietnamese defeated the French. It was passed on to Kennedy, who kept it limited to advisors, training the South Vietnamese to fight. Johnson inherited it, and promptly escalated it so American troops were doing most of the fighting. Nixon took over, maintained it until he realized the war was a big loser, and ended our involvement, leaving the South vietnamese government to sink or swim. They sank.
People in this thread sure do seem to be in a charitable mood, btw ... first Miner's attempt to portray Ho as reasonable enough for the U.S. to work with, your description of Nixon as something other than someone who was lying about Vietnam from before his election and never, ever quit.