No, but it is technically a "neo-colony" of the USA - which means it is still highly dependent on the United States in defense and security. Same goes for all previously American-occupied territories in Asia such as the Philippines and South Korea.
But yes, between 1945-1950, it was technically governed by the Americans as a protectorate. Korea was also governed as a protectorate from 1945-1949, while the Philippines as everybody knows, was an American Military Territory from 1898-1902, then governed as an American colony from 1902-1935, then as an American commonwealth/protectorate from 1935-1941 and 1945-1946.


