BEIRUT -- The first Syrian rebel group to be given U.S. weapons collapsed Sunday after losing control of its headquarters to Syria's main al-Qaeda affiliate, further complicating American-led efforts to counter the rise of extremism in Syria.The rout of Harakat Hazm, whose name means Steadfastness Movement, culminated months of clashes with the al-Qaeda-linked Jabhat al-Nusra in which the moderate group first was pushed from its main headquarters in the northern Syrian province of Idlib and then was ousted Sunday from its new base in the province of Aleppo.
After losing this latest battle, Hazm said in a statement circulated on social media that the movement had been dissolved "in an effort to halt the bloodshed" and that surviving members would be absorbed into a new rebel coalition called the Shamiyah Front.
Nusra fighters boasted on Twitter that they had seized control of U.S.-made TOW anti-tank missiles and other American aid provided to Hazm when they overran the rebels' headquarters in the town of Atarib in the province of Aleppo. The claims could not be verified, and American supplies of weaponry to moderate rebels in northern Syria had in any case been scaled back in recent months since the battles with Nusra began.
The collapse comes as the Pentagon embarks on a new effort to train moderate rebels to fight the Islamic State, a different extremist group that is at odds with Jabhat al-Nusra and has severed ties with al-Qaeda.
Hazm, which once claimed to have 5,000 fighters, had received U.S. weapons under a separate covert program launched last year by the CIA that was intended to bolster moderate rebels and put pressure on President Bashar al-Assad to compromise with the opposition.
Since Islamic State fighters surged into the Iraqi city of Mosul last summer, the Obama administration has refocused its Syria policy in ways that emphasize defeating the Islamic State rather than pressuring Assad to step down.