US airstrike hits pro-Syria government forces for first time

BEIRUT (AP) — A U.S. airstrike struck pro-Syrian government forces that the coalition said posed a threat to American troops and allied rebels operating near the border with Jordan on Thursday, the first such close confrontation between U.S. forces and fighters backing President Bashar Assad.

The coalition said "apparent" Russian attempts to stop pro-Assad forces from moving toward Tanf, as well as warning shots and a show of force, had failed.

American officials and Syrian activists said the strike hit in the desert near the border with Jordan, though it was unclear if it struck the Syrian army or just militias allied with the government.

The region around Tanf, where the borders of Jordan, Syria and Iraq meet, has been considered a de-conflicted zone, under an agreement between the U.S. and Russia.

Speaking to reporters, Defense Secretary Jim Mattis said the U.S. will defend its troops in case of "aggressive" steps against them. He was asked if the airstrike increases the U.S. role in the Syrian war.

"We are not increasing our role in the Syrian civil war, but we will defend our troops," Mattis said. "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 "defensive" strike was also an apparent signal to Assad to keep his forces out of a zone where U.S.-backed rebels are fighting the Islamic State group.

"This action was taken after apparent Russian attempts to dissuade Syrian pro-regime movement south ... were unsuccessful, a coalition aircraft show of force, and the firing of warning shots," the U.S.-led coalitions aid. It said coalition forces have been operating in the area "for many months training and advising vetted partner forces" in the battle against IS.

The U.S. strike marks a new approach in what has become an intensely crowded and complicated war zone. Thursday's strike was the coalition's first on pro-Assad forces in the battlefield. The coalition had so far kept its military operations focused on Islamic State militants and al-Qaida-linked groups.

Last month, the U.S. fired 59 missiles at a government air base in central Syria as punishment for a chemical attack blamed on Assad's forces that killed nearly 90 people.