BEIRUT (AP) — Artillery hit a base housing U.S. troops in eastern Syria early Thursday, lightly injuring two members of the U.S.-led coalition there, the organization said.

The attack — two rounds of indirect fire — was the first to hit the base in Syria's Deir el-Zour province since January, when eight rounds landed inside its perimeter.

The International Coalition for Operation Inherent Resolve said troops at Green Village in the province that borders Iraq reported receiving two rounds of indirect fire. Two Coalition members were lightly injured in the attack, it added, saying that both were treated and returned to duty Thursday morning.

Green Village, just east of the Euphrates River, is an installation used by some of the several hundred U.S. forces in Syria.

The coalition said the incoming rounds ignited two fires which were quickly extinguished.

The Britain-based Syrian Observatory for Human Rights, an opposition war monitor, said five rockets were fired early Thursday from positions where Iran-backed fighters are based.

Hundreds of U.S. troops are stationed in northeastern Syria, working with the U.S.-backed and Kurdish-led Syrian Democratic Forces to fight against the Islamic State group.

Thousands of Iran-backed militiamen from around the Middle East are deployed in different parts of Syria, many of them in areas along the border with Iraq.

Iran sent thousands of fighters it backs from around the Middle East to fight alongside President Bashar Assad’s forces during Syria’s 11-year conflict. They helped tip the balance of power in his favor.