U.S.-backed forces in Syria are making what could be a final push this week to recapture the remaining ISIS-held portions of Raqqa. The city has been the de-facto Syrian capital of the terrorist group since 2014.

The Syrian Democratic Forces (SDF), are a coalition of Kurdish and other fighters backed by the U.S. and its allies who have been fighting ISIS in the Syrian civil war. SDF soldiers have surrounded ISIS fighters in a small part of the city, according to Reuters. U.S.-led airstrikes have been bombarding the city for months.

“[ISIS] regularly launch small raids, even behind our position. Yesterday they attacked the building opposite and tried to push toward us. We killed a few and they retreated to the hospital,” said an ADF soldier using the pseudonym Babel, to Reuters.

ISIS fighters are holding civilians hostage in the few buildings including a hospital and a stadium that remain in their control in Raqqa.

“The [SDF] are reinforcing positions ahead of the final attack on the city of Raqqa,” said Mustafa Bali to the Associated Press Monday. A U.S. spokesperson was more cautious.

“Whether this is the final assault or an assault, I won't characterize it either way,” said Ryan Dillon speaking for the U.S. coalition to Reuters. “[The fight is]concentrated around the complex which was the national hospital and the stadium.”

SDF predicted in June that a major push would take back the city in weeks. The prediction proved to be wrong. ISIS militants have used civilians for cover, set booby traps and employed sniper fire, slowing SDF.

ISIS has seen major setbacks in the region this year. They lost another major stronghold, Mosul, Iraq, in July. Complicating matters is the ongoing civil war in Syria. Russian backed soldiers of Bashar al-Assad's Syrian army have also been making inroads against ISIS in the area. Both sides agreed to a buffer while fighting ISIS.