WASHINGTON — The United States has started drawing down hundreds of troops from northeastern Syria, a reflection of the shifting security environment in the country since the fall of President Bashar Assad in December, but also a move that carries risks.

The military is shuttering three of its eight small operating bases in the country’s northeast, reducing troop levels to about 1,400 from 2,000, two senior U.S. officials said. The bases are Mission Support Site Green Village, MSS Euphrates and a third much smaller facility.

After 60 days, the officials said, U.S. commanders will assess whether to make additional cuts. Commanders have recommended keeping at least 500 U.S. troops in Syria, one of the officials said.

President Donald Trump, however, has expressed deep skepticism about keeping any U.S. troops in the country. At least for now the reductions that started Thursday are based on ground commanders’ recommendations to close and consolidate bases, and were approved by the Pentagon and its Central Command, the officials said, speaking on the condition of anonymity.

— The New York Times