U.S. aircraft bombed al-Qaida’s Syrian branch as well as another hard-line rebel faction in northwestern Syria early on Thursday, activists said, in an apparent widening of targets of the American-led coalition against the Islamic State extremist group.

The series of airstrikes overnight targeted three different areas near the Turkish border, hitting a headquarters and a vehicle belonging to the al-Qaida-affiliated Nusra Front as well as a compound of the deeply conservative Ahrar al-Sham rebel group. It marked only the second time the United States had expanded its aerial campaign against Islamic State militants to hit other extremists in Syria.

There was no immediate confirmation from U.S. officials, but the apparent strikes took place amid a Nusra Front offensive that has routed Western-backed rebel groups from their strongholds in Syria’s Idlib province near the Turkish border. The timing suggests that Washington could be trying to curb the militant assault and destroy weapons supplies of hard-line rebels and al-Qaida fighters. […]