ISIS Stronghold of Raqqa Surrounded by U.S.-backed Forces as Noose Tightens

Strategic maneuver to cut off group comes as Iraqi forces declare victory over group in Mosul

A Kurdish fighter from the People's Protection Units (YPG) fires heavy machine-gun at Islamic State militants in Raqqa, Syria June 21, 2017.

U.S.-backed forces on Thursday fully encircled the ISIS-held city of Raqqa after closing the militants' last way out from the south, the Syrian Observatory for Human Rights monitoring group said. 

The Syrian Democratic Forces, an alliance of Kurdish and Arab fighters that launched a long-anticipated assault on the Islamists' de facto Syrian capital this month, had earlier said they were on the point of cutting off Raqqa's last exit. 

ISIS also lost ground in Iraq on Thursday, where government forces announced they had captured the famed mosque where the organization's leader declared the establishment of a caliphate in 2014.