What does the acronym in the TV series "The Man from U.N.C.L.E." mean?

The Man from U.N.C.L.E. is an American television series that was broadcast on NBC from September 22, 1964, to January 15, 1968. It followed secret agents, played by Robert Vaughn and David McCallum, who worked for a secret international counter espionage and law enforcement agency called U.N.C.L.E. Originally, co-creator Sam Rolfe wanted to leave the meaning of U.N.C.L.E. ambiguous so it could refer to either "Uncle Sam" or the United Nations. Concerns by the Metro-Goldwyn-Mayer legal department about using "U.N." for commercial purposes resulted in the producers' clarification that U.N.C.L.E. was an acronym for the United Network Command for Law and Enforcement. Each episode had an "acknowledgement" to the U.N.C.L.E. in the end titles.