RAQQA, Syria, May 24 (UPI) -- U.S.-backed Kurdish and Arab forces pushed into territory north of the Islamic State's de facto capital in Raqqa, Syria on Tuesday.
The Syrian Democratic Forces, a U.S-backed coalition of armed groups led by the Kurdish People's Protection Units, said it mobilized several thousand fighters north of Raqqa.
Idriss Nassan, a spokesman for the Kurds in Kobani, Syria, said some clashes are taking place in villages around Ain al Issa, 30 miles north of Raqqa.
Russia is ready to coordinate efforts with the coalition, Russian Foreign Minister Sergey Lavrov said Tuesday. "I cannot say how real reports are that such actions have already begun, but we are ready for such coordination," Lavrov said in Uzbekistan.
U.S. coalition spokesman Col. Steve Warren said the coalition has "always been focused on evicting ISIS" from Raqqa. "We will continue to support the [Syrian Democratic Forces] as they conduct ground operations to further isolate the city."
He added that the coalition will continue to provide air support against IS.
IS, also known as ISIS, ISIL and Daesh, captured Raqqa during its advance through Syria and Iraq in 2014.
The offensive comes as Iraqi forces are trying to oust IS from Fallujah, west of Baghdad.