One Army officer who has deployed to northeastern Syria and has knowledge of the situation said that multiple rounds of 155 mm fire were launched from Turkey’s side of the border and that they had a “bracketing effect” in which shells landed on both sides of the U.S. outpost.

“That’s an area weapon,” the officer said, noting its explosive effects. “That’s not something we ever would have done to a partner force.”

The officer said Turkey knew there were Americans on the hill and that it had to be deliberate. The service members vacated the outpost after the incident but returned Saturday, according to a U.S. official and images circulating on social media.

“We had been there for months, and it is the most clearly defined position in that entire area,” the officer said.