Warplanes believed to be part of a U.S.-led alliance struck Nusra Front positions in northern Syria on Friday following an attack by the al Qaeda-linked group on Western-backed rebels in the area, a group tracking the war

The Syrian Observatory for Human Rights, a UK-based group that reports on the war, said the air strikes hit Nusra Front positions near the town of Azaz, north of Aleppo.

Overnight, the Nusra Front had launched an attack in the area targeting rebels including a group said by opposition sources to have been trained under a U.S.-led program to build a force to fight Islamic State of Iraq and Syria (ISIS), the Observatory reported. […]