U.S.-led aircraft struck a column of pro-Syrian government forces advancing toward a small U.S. outpost in southeastern Syria on Tuesday, the Pentagon said in a statement.
The strike marks a second time in less than a month that U.S. aircraft have targeted troops aligned with Syrian President Bashar al-Assad. Both times, the Pentagon said, were in self-defense.
The statement said the U.S.-led coalition communicated with the advancing forces through an existing hotline set up to ensure that Russian and U.S. aircraft can operate safely in Syrian airspace. Despite the warnings, the Syrian forces continued to advance, prompting the U.S.-led coalition to destroy two artillery pieces and an anti-aircraft weapon, according to the statement. A tank was also damaged.
It is unclear how many troops were killed or wounded in the bombing run and what legal rationale might cover the U.S.-led forces continued strikes on Syrian government forces operating within their borders.
“We are not increasing our role in the Syrian civil war, but we will defend our troops,” Defense Secretary Jim Mattis told reporters after the May strike. “And that is a coalition element made up of more than just U.S. troops, and so we will defend ourselves [if] people take aggressive steps against us.”
The Tanf outpost, located near the Syrian, Iraq and Jordanian border, has become a flashpoint in the six-year old Syrian conflict in recent weeks. Iranian-backed Shiite militias loyal to Assad, along with Syrian government forces, are making a concerted push to recapture territory from the Islamic State in the area in a likely attempt to secure the border and the desert highway that runs into Iraq.
Meanwhile, the U.S.-led coalition and a contingent of U.S. and British Special Operations troops have been training a detachment of Syrian fighters there to ultimately lead an offensive into the Euphrates River valley.