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A major U.S.-backed offensive to oust ISIS from its capital of Raqqa, Syria has begun, it was announced early Sunday.

The Kurdish-dominated Syria Democratic Forces (SDF) coalition told a news conference that the goal of the operation, called Angry Euphrates, would be liberating the Syrian city from the militants.

A 2014 file photo of a minaret destroyed in air strikes by Syrian army warplanes in Raqqa, Syria. Anadolu Agency / Getty Images

The offensive, which comes two weeks after a campaign to clear ISIS from Mosul, Iraq, will be supported by U.S. air strikes and involved 30,000 fighters, the SDF told reporters.

Residents in the city were warned to stay away from gathering places as those will be targets during the operation.

Warplanes believed to belong to the International Coalition bombed places controlled by the “Islamic State” in Laqta area to the northeast of Raqqa but there was no immediate word on casualties, according to the U.K-based Syrian Observatory for Human Rights.

The move to liberate the city was signaled at the end of last month by Defense Secretary Ash Carter in an interview in Paris with NBC News.

The city is the de facto capital of the extremists' so-called caliphate which stretches from Syria into Iraq.