People inspect a hole in the ground filled with water in a damaged site after airstrikes on the rebel held Tariq al-Bab neighbourhood of Aleppo, Syria September 23, 2016. REUTERS/Abdalrhman Ismail

With a ceasefire in tatters, American-backed Kurdish and Arab rebels are moving south while Russian and Syrian government forces are advancing quickly north. In the middle is Aleppo, which has faced some of the harshest bombardment it has seen in months.

In Aleppo itself, Jabhat Fatah al-Sham, formerly known as al-Qaeda affiliated Jabhat al-Nusra, is rejecting cooperation with any side.

The imminent confrontation could mark a turning point in the prolonged Syrian civil war, and will determine which direction the scales are tipping.

Reports from the Syrian Observatory for Human Rights, an independent monitoring group that relies on local accounts to document airstrikes and military operations within Syria and Iraq, reports that scores died in a flurry of airstrikes overnight on Thursday that carried into Friday morning. As many as 50 were killed in and around the city, although the death toll is expected to rise.

The strikes focused heavily on Aleppo's east, where rebels have managed to maintain control.

The Observatory reported that the strikes were carried out by Russian aircraft, although it is unclear the role the Syrian air force may have played. Artillery fire added to the aerial bombardment, Reuters reported.

But as Russian and Syrian forces move to re-take all of Aleppo, American special forces have embedded with the Syrian Democratic Forces — a predominantly Kurdish force with Arab units — to retake land from north of Aleppo, near the Turkish border.

Last week, the United States announced that it would be boosting its special forces contingent in northern Syria, and would begin cooperating with Turkish soldiers.

But while the Kurds and Turks, with American help but operating entirely separately, are pushing IS units out of territory northwest of Aleppo, that mission led to an awkward confrontation between American forces and Syrian rebels in the town of al-Rai last week. An American military source confirmed to VICE News that the American special forces are also helping in the fight against al-Sham in territory they control north-east of Aleppo.

In a nod that the confrontation seems to be coming to a head, al-Sham released a statement that called on its fighters and supporters to fight against all forces trying to enter the city. The statement comes in response to Ahrar al-Sham, an allied group, which has called for cooperation with Turkish forces.