It actually dates back to the 30's; if you look back far enough, you'll see it more as Vietnam's War of Independence - an attempt to shake off foreign occupiers, be it France, Japan, or, later, the US. Lost in all the Cold War FUD and Domino Theories is Ho Chi Minh's pro-Americanism; he was an admirer of the Declaration of Independence, and once thought that gaining US Commonwealth status (like Puerto Rico) was the best way to transition Vietnam to nationhood.