BEIRUT—A facility housing U.S. troops in eastern Syria came under attack late Sunday when rockets were fired from nearby areas, an opposition war monitor, state media, and a spokesman for U.S.-backed fighters said, though the U.S. military denied there was any attack. “There is no truth to the reports that U.S. forces in Syria were attacked by rockets today,” wrote coalition spokesman Col. Wayne Marotto on Twitter. Earlier Sunday, Siyamend Ali, a spokesman for the U.S.-backed and Kurdish-led Syrian Democratic Forces, said two rockets were fired at al-Omar field in Syria’s eastern province of Deir el-Zour without inflicting any casualties. He added that it was not immediately clear where the rockets were fired from. The Britain-based Syrian Observatory for Human Rights said the rockets were fired from areas controlled by Iran-backed fighters in the area of Mayadeen, also in Deir el-Zour. Syria’s state news agency, SANA, also reported that al-Omar …