Complex sentence: Its U.S. service was quickly wound down after 1965, and the last USAF Starfighters left active service in the Regular Air Force in 1969, but continued in use with the Puerto Rico Air National Guard until 1975.
Split into simpler sentences: Its U.S. service was quickly wound down after 1965, and the last USAF Starfighters left active service in 1969. It continued in use with the Puerto Rico Air National Guard until 1975.