The Nusra Front says in a statement today it is against its religion to join the US-led coalition or be aided by it.
In a major policy shift, Turkey agreed last month to allow the United States to use the strategic Incirlik Air Base to launch airstrikes against IS and agreed on the outlines of a plan to rout the extremists from a stretch of Syrian territory along the Turkish border.
Nusra Front says other insurgent groups are replacing it in northern Aleppo.