At last eleven people were killed in a U.S led air strike in northeast Syria, the Syrian Observatory for Human Rights said.
The bombing came a day after one U.S trooper was killed by Iran backed militia, U.S said.
U.S. and Iran have traded strikes in Syria several times, however, the latest attack threaten to upend recent efforts to deescalate tensions across the wider Middle East, whose rival powers have made steps toward détente in recent days after years of turmoil.
U.S. Defense Secretary Lloyd Austin said in a statement that the American intelligence community had determined the drone was of Iranian origin, but offered no other immediate evidence to support the claim. The drone hit a coalition base in the northeast Syrian city of Hasaka. The wounded included five American service members and a U.S. contractor.
Austin said the strikes were a response to the drone attack “as well as a series of recent attacks against coalition forces in Syria” by groups affiliated with the Revolutionary Guard, reported Associated Press.
The U.S. has its forces in northeast Syria since 2015 and maintains some 900 troops in the country.
The U.S. airstrikes hit targets in three towns in eastern Syria, activists said.
Overnight, videos on social media purported to show explosions in Deir el-Zour, a strategic province that borders Iraq and contains oil fields.
The activist group Deir Ezzor 24, which covers news in the province, said the American strikes killed four people and wounded a number of others, including Iraqis.
The Syrian Observatory for Human Rights, an opposition war monitor, put the death toll from U.S. strikes at 11 Iranian-backed fighters — including six at an arms depot in the Harabesh neighborhood in the city of Deir el-Zour and five others at military posts near the towns of Mayadeen and Boukamal.