The United States was a long term ally with France. France was the sole country which supported its independence from Britain. It would be foolish to dissolve an alliance with one they had supported for so long. Additionally, this was during the era of the Cold War and the Red Scare. The leader of Vietnam Ho Chi Minh (?) was a communist. Mind you most Americans were afraid of communism due to its association with Russia. The United States found it wise to avoid sending support for a communistic country (Vietnam).
