The presence of H.T.S. has been a chief justification cited by the Syrian government and its most powerful ally, Russia, for the scorched-earth bombing campaign they are carrying out in Eastern Ghouta. The campaign has killed more than 1,000 people, most of them civilians, in less than a month, according to medical staff and monitoring groups in the area.
The cease-fire endorsed more than a week ago by the United Nations Security Council — but not yet implemented — does not cover H.T.S., a coalition of rebel forces led by the Nusra Front, a group that was formed as Al Qaeda’s Syria affiliate and is listed internationally as a terrorist group.
Russia and the Syrian government say the other rebel groups have worked with H.T.S. and so are fair game for attacks. During rebel infighting in the enclave, analysts and some residents say, the Army of Islam’s main rival, Faylaq Al Rahman, has sometimes formed opportunistic alliances with H.T.S.
Mohammad Adel, an antigovernment activist in Douma, said H.T.S. had endangered people in Eastern Ghouta, declared Muslims who disagree with the group nonbelievers, and soured residents on the other rebel groups.
“it was behind many assassinations, and the killings which happened between the groups in Ghouta,” Mr. Adel said in an online interview. “So Ghouta will gain by finishing with these people.”
Yet the pro-government alliance is not likely to stop at the evacuation of H.T.S. fighters. It often refers to all rebels as terrorists and is looking instead to take back the entire area.
To keep bombing, Mr. Adel said, “the Russians don’t need any excuse.”