Pentagon officials told The Daily Beast that the U.S. military was reassessing its air war over Syria after Moscow hinted it might shoot down American warplanes there.

“We’re taking prudent measures to reposition over Syria,” Defense Department spokeswoman Dana White told The Daily Beast. “We always take proper measures depending on the situation on the ground, but we’re still operating… throughout Syria,” she said. “We always reserve the right to defend ourselves and our coalition partners.”

Over the weekend, the U.S. took out a military jet belonging to the Syrian military, a Russian ally. That prompted Moscow to warn that “the destruction of the aircraft of the Syrian Air Force by the American aviation in the air space of Syria is a cynical violation of the sovereignty” and an “an act of military aggression against the Syrian Arab Republic,” the official statement posted on social media read.