Islamic State kills four security personnel in Syria, state news agency says

Islamic State militants killed four Syrian government security personnel in northern Syria on Monday, the Syrian state news agency reported, in what would be the group's deadliest attack on government forces since the ouster of President Bashar al-Assad.

The assault on a checkpoint west of Raqqa city underlined an escalation in attacks by the jihadist group against President Ahmed al-Sharaa's government, two days after the jihadist group declared "a new phase of operations" against it.

Islamic State issued no immediate claim of responsibility for Monday's attack. On Saturday, the group claimed two attacks targeting Syrian army personnel in northern and eastern Syria, in which a Syrian soldier and a civilian were killed.

The Syrian state news agency said forces foiled Monday's attack and killed one of the militants. It quoted a security source as saying Islamic State carried out the attack.

The Syrian government joined the U.S.-led coalition to combat Islamic State last year. In January, government forces seized control of Raqqa from the Kurdish-led Syrian Democratic Forces, along with much of the surrounding territory in northern and eastern Syria.

Meanwhile, U.S. forces on Monday began withdrawing from their largest military base in the northeast, according to three Syrian military and security sources - part of a broader pullout of U.S. troops who deployed to Syria a decade ago to fight Islamic State.