BEIRUT, Lebanon — Syria on Monday said a United States-led coalition had bombed a Syrian military base in the east of the country, killing three soldiers, wounding at least 13 and destroying vehicles and equipment. The United States denied the Syrian accusation and said a Russian warplane appeared to have been responsible.

The Syrian accusation, in a statement carried by the official news agency, was the first time that President Bashar al-Assad’s government had held the Americans responsible for bombing a Syrian military facility since the United States began airstrikes against Islamic State targets in Syria more than a year ago.

The statement said that the bombing had been conducted Sunday evening in Deir al-Zour Province, and that Syria had sent letters of protest to the United Nations calling it “a heinous aggression by the coalition.”

American military officials said the coalition had carried out airstrikes in the province on Sunday, but they said no Syrian military positions had been struck. The Americans seemed anxious to avoid an escalation of tensions with Mr. Assad’s government.