Why did america return vietnam to french colonial rule?

N 1940, France was swiftly defeated by Nazi Germany, and colonial administration of French Indochina (modern-day Vietnam, Laos and Cambodia) passed to the pro-German Vichy French government. Later that year, the Vichy government ceded control of Hanoi and Saigon to Japan; and in 1941, Japan extended its control over the whole of French Indochina. The United States, concerned by this expansion, put embargoes on exports of steel and oil to Japan. The desire to escape these embargoes and become resource self-sufficient ultimately led to Japan's decision on December 7, 1941 to attack the British Empire in Hong Kong, Malaya and Singapore and simultaneously the USA at Pearl Harbor, Hawaii. This led to the USA declaring war against Japan. The US then joined the British Empire, already at war with Germany since 1939, and its existing allies in the fight against the Axis nations.[1]