TEHRAN (Press Shia Agency) – Syrian Kurdish troops launched an offensive Sunday on Daesh’s (ISIL or ISIS) de facto Syrian capital Raqqa, upping pressure on the terrorists after Iraqi forces entered their Iraqi bastion Mosul.

"The major battle to liberate Raqqa and its surroundings has begun," Jihan Sheikh Ahmed, a spokeswoman for the US-backed Kurdish-Arab alliance, known as the Syrian Democratic Forces (SDF), said at a press conference in Ain Issa, some 50 kilometers (30 miles) north of the extremist bastion, AFP reported.

The operation, dubbed "The Wrath of the Euphrates," involves some 30,000 fighters and had begun Saturday night, Ahmed said.

SDF spokesman Talal Sello added that it would proceed in two phases, first seizing areas around Raqqa and isolating the city, then "taking control of the city" itself.

"The fight will not be easy, and will require accurate and careful operations because ISIS will defend its bastion knowing that the loss of Raqqa will mean it is finished in Syria," he said.

The long-awaited operation comes two years after Daesh seized control of large parts of Syria and Iraq and declared its so-called "caliphate".

The terrorists have suffered a string of territorial defeats in recent months and are under pressure on multiple fronts.

After launching an offensive on Mosul on Oct. 17, Iraqi Special Forces pushed into the city Friday and have been advancing on different fronts.