U.S.-backed Kurdish-Arab forces launched an offensive Sunday on the Islamic State group's de facto Syrian capital Raqa, upping pressure on the jihadists who are already battling Iraqi troops in Mosul.
The start of the assault by the Syrian Democratic Forces (SDF) came as Iraqi forces fought inside Mosul for the third day running, with the jihadists putting up fierce resistance.
The two cities are the last major urban centers under IS control after the jihadists suffered a string of territorial losses in Iraq and Syria over the past year.
The U.S.-led coalition battling IS is backing both assaults, hoping to deal a knockout blow to the self-styled "caliphate" the group declared in mid-2014.
Lined up in crisp fatigues at an outdoor press conference, SDF commanders announced the start of the operation against Raqa in Ain Issa, some 50 kilometers (30 miles) north of the city.