Three Syrian soldiers were killed and 13 wounded in an airstrike on Sunday night. The Syrian government in Damascus has accused the U.S.-led coalition of the bombing, the Associated Press reports, but a senior U.S. military official said the Pentagon was “certain” it was the Russians.

President Bashar Assad’s government said that four coalition aircraft bombed the army camp in Deir el-Zour, an eastern city, causing casualties and destroying munitions.

“This hampers efforts to combat terrorism and proves once again that this coalition lacks seriousness and credibility to effectively fight terrorism,” Syria said in a letter to the United Nations, published in state media. According to the AP, the government refers to all anti-Assad forces as “terrorists.”

In a statement, the New York Times reports, the Combined Joint Task Force said that the coalition had carried out airstrikes on Sunday, but that they were “all against oil well heads” some 35 miles from the base.

“We did not strike any vehicles or personnel targets in this area,” the statement read. “We have no indication any Syrian soldiers were even near our strikes.”

From the Times:

A senior United States official later attributed any deaths and any damage to the Syrian base to what he called “a screw-up” by the Russians, who joined the Syria war in September as allies of Mr. Assad and have conducted airstrikes with Backfire bombers and other aerial armaments.

“We’ve got a radar track showing a Backfire bomber flying directly over the town that the Syrians named a few minutes before the first claims that we killed some Syrian troops,” the American official said, speaking on the condition of anonymity to discuss operational details.

Meanwhile, The Guardian reports, at least 26 Syrian civilians were killed in what is believe to have been a coalition airstrike against the northeastern village of Al-Khan. ISIS does control Al-Khan, said the Syrian Observatory for Human Rights’ Rami Abdel Rahman, but only on the outskirts—“which is why all of the deaths were civilians.”

Photo via AP Images. Contact the author of this post: brendan.oconnor@gawker.com.