Gates, speaking ahead of the start of President Barack Obama's planned troop cuts in Afghanistan next month, said a "rush to the exits" would jeopardize military progress in Afghanistan.
"We are making substantial military progress on the ground...these gains could be threatened if we do not proceed with the transition to Afghan security lead in a deliberate, organised, and coordinated manner," he told a news conference after a meeting of NATO defense ministers in Brussels.
"Even as the United States begins to draw down next month, I assured my fellow ministers that there will be no rush to the exits on our part, and we expect the same from our allies."
NATO Secretary-General Anders Fogh Rasmussen told a news briefing the NATO ministers all pledged no such rush to leave at the Brussels meeting and that he was confident Washington would base its plans on security conditions in the country.
Obama is expected to announce he will bring a sizable number of the 100,000 U.S. troops in Afghanistan home starting in July and U.S. lawmakers have been piling pressure on him to accelerate the end to a long, costly war.
Washington's NATO allies are also keen to get their troops home, but some expressed concern in Brussels about the impact on the 10-year-old Afghan mission of too deep a cut in U.S. troop numbers.