The US-backed Syrian Democratic Forces (SDF) rebel force against the government of Assad has cautiously entered the final Islamic State stronghold of Raqqa. They entered thru the eastern edge of the city, fording a river on foot and in light vehicles all the while relaying their position by radio in an attempt not to fall victim to friendly artillery fire.

Raqqa is considered by the Islamic State, (IS) to be their “caliphate” and their “capital” in Syria. The eastern edge of the city, al Mishlab, is just the beginning of what is forecast to be a long and difficult battle.

The Syrian Democratic Forces (SDF) launched their assault to capture the city this week.

As artillery and coalition aircraft pounded targets in the city, SDF fighters moved in small groups into the district during a media trip organized by the SDF.

“The comrades are advancing and Daesh forces are collapsing in front of us, but there are snipers obstructing our movements, and they are also shelling our positions with mortars,” said an SDF fighter who gave his name as Khalil.

For months, air strikes and special forces from the U.S.-led coalition have helped them encircle Raqqa, which Islamic State seized in 2014 and has used as a base to plan attacks abroad.

In a statement sent to Reuters, coalition spokesman Colonel Joseph Scrocca said the militants’ resistance had been “minimal” outside the city and that they were retreating “to protect their fortifications inside the city”.

A few civilians left farmland near Raqqa on Wednesday, waving white flags to SDF fighters heading toward al-Mishlab on a road littered with blown-up vehicles.