U.S.-backed militias seized Syria’s biggest oil field from Islamic State fighters Sunday, dealing another crippling blow to the terrorist state just days after it was driven from its main stronghold in Raqqa.

The Syrian Democratic Forces (SDF) say they captured the al-Omar oil field in the early morning hours, driving ISIS militants into buildings in a nearby district. SDF troops are currently hunting down the remaining ISIS fighters in the area.

“Our forces managed to liberate the fields without notable damages,” said Lilwa al-Abdallah, spokeswoman for the SDF offensive, according to Reuters.

The al-Omar oil field has been one of ISIS’s most lucrative sources of revenue since the group captured it in 2014. ISIS militants have propped up their now-crumbling caliphate by selling al-Omar oil to Iraqi traders, middlemen from the Bashar al-Assad’s government and businessmen exporting to Turkey, according to the Wall Street Journal.

The capture of the oil field comes shortly after SDF completed its months-long operation to liberate Raqqa, the capital of the ISIS “caliphate” in Syria. Following the victory in Raqqa, SDF moved farther into eastern Syria to drive ISIS from its last remaining footholds in the oil-rich Deir al-Zour province, which borders Iraq.

As the U.S.-backed SDF continues to squeeze ISIS in eastern Syria, the Syrian army, supported by Russian air power and Iranian-affiliated militias, is carrying out its a separate offensive against the group in the western part of the country,

The U.S.-led coalition and Russian military officials have been holding deconfliction meetings to avoid clashes between their forces, but the two operations have come into conflict as the Syrian regime regains territory once held by ISIS.

Last month, a Russian airstrike hit and wounded several SDF fighters in Deir al-Zour. No U.S. troops were injured, but the incident sparked talks between the highest levels of the Pentagon and State Department and their Russian counterparts.

Follow Will on Twitter

Send tips to will@dailycallernewsfoundation.org.

Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please contact licensing@dailycallernewsfoundation.org.