Syrian rebels are expressing growing anger about the way the US airstrikes in Syria have gone, complaining that not only did the US not strike Syrian military targets, but that they also attacked al-Qaeda’s Khorasan group.

That’s not the US intervention the rebels thought they were signing on for, and they warned that the US targeting of al-Qaeda’s Jabhat al-Nusra and its compatriots is doing serious damage 5to “moderate” rebels.

The Nusra Front and other Islamist factions have been withdrawing their heavy weapons from northern Syria, particularly the tenuously held Idlib Province, saying they don’t want to be targeted. That’s likely to give Assad forces an opening to retake more lost ground.

The level to which the Free Syrian Army and other factions backed by the US depend on al-Qaeda and ISIS underscores the complexity of the US air war. It’s also likely to fuel more anger from the “pro-US” rebels because the air war really is helping the Assad government on the ground.