The United States did not support independence movements after World War II (1939–1945) for several reasons. First, the Cold War dominated Washington's foreign policy planning. Several of America's key allies, particularly France, sought to retain control of its colonies. The US wanted to forge a strong coalition against communism, so it did not help subjects attain their independence. Supporting revolutions would upset Cold War allies and lead to the creation of new nations that might choose communism instead of capitalist democracy. In addition, economic interests figured into Washington's support of old regimes.
America's support of French efforts in Indochina was a tragic mistake which ultimately led to the Vietnam War (1957–1975). France fought to keep its colony from 1946 to 1954. Washington gave the French a great deal of economic support and even considered intervening militarily before the ultimate French defeat in 1954. France's enemy, Ho Chi Minh, was both a communist and a nationalist, but Ho's nationalism was never appreciated by Washington. France struggled and failed again in Algeria, another French colony that fought for—and ultimately won—independence.
Cuba was a de-facto American colony before Fidel Castro took it over in 1959. American businesses dominated the island's economy, and Washington ignored the abuses carried out by Fulgencio Batista, the Cuban dictator.
In general, military alliances, security considerations, and economics mattered more to American leaders than the aspirations of oppressed peoples.