President Bashar al-Assad’s refusal to step down and open the door to compromise is not the only obstacle to a resolution of the Syrian conflict. Various Islamist groups focused on outright military victory also play a major role. Since 2012 they have come to dominate the uprising. The international community agrees that there can be no negotiations with the so-called Islamic State in Iraq and Syria (ISIS), nor with the al Nusra Front, which is close to al-Qaeda. The open question is how to treat Ahrar al-Sham, as the largest rebel group alongside ISIS. Its militant Salafist orientation, which makes it the al-Nusra Front’s closest ally, speaks against involving it in talks. Although Ahrar has been seeking since 2015 to position itself as a partner for the United States and its allies, there is no sign that it intends to abandon its alliance with the jihadists.