From
http://www.fsmitha.com/h2/ch26.htm....In May 1945, the Truman administration gave France its approval to resume colonial authority in Indochina, Truman hoping that France would liberalize its rule there. In that part of Indochina called Vietnam, the French were already facing a declared independence. A movement called the Viet Minh, led by Ho Chi Minh, a veteran Communist, had been fighting the Vichy French regime in Vietnam, which was administering Indochina for Japan. And the Viet Minh had been helping the Americans by rescuing downed U.S. airmen. At the end of the war the Viet Minh had committees throughout Vietnam, and Ho Chi Minh announced Vietnam's independence. Most Vietnamese were overjoyed and looked upon the Viet Minh and Ho Chi Minh as heroes. This was the nationalist aspect that U.S. forces in Vietnam would be fighting. In spirit, Vietnam was independent of foreign rule. But the Truman administration and the other Allied powers repeated the policy of the Allied powers at the end of World War I. They ignored the wish of the Vietnamese to be independent. The French tried to force their way back in Vietnam, and a war between the French and the Viet Minh began in December 1946.
The United States helped the French in Vietnam, President Truman doing so for the sake of the fight against communism in Europe and in Indochina. Much of France's efforts to overthrow Ho Chi Minh's government in Vietnam was being financed by the United States, and around 1950 the Viet Minh began to benefit from the coming to power of the communists in China. After North Korea invaded South Korea in 1950, Secretary of State Dean Acheson persuaded Truman to increase U.S. assistance to the French, and the United States recognized France's puppet king in Vietnam, Bao Dai. After Eisenhower took office in 1952, U.S. aid to the French effort in Vietnam increased, and by 1954, U.S. aid amounted to 80 percent of the costs of the French effort....
Etc.
And we know how well that turned out.