Reuters reports: U.S.-backed rebels said on Sunday they were launching an operation to retake the Syrian city of Raqqa, the de facto capital of Islamic State.

The attack ratchets up pressure on the militant group at a critical moment, with its fighters already battling an offensive by Iraqi security forces on their remaining Iraqi stronghold in the northern city of Mosul.

The U.S.-backed Syria Democratic Forces (SDF), an alliance of Kurdish and Arab armed groups, first announced on Sunday that a campaign to retake Raqqa would begin within hours, with U.S. forces providing air cover. Soon afterwards, it said that the operation, called Euphrates Anger, had begun. [Continue reading…]