Islamic State (IS) militants took back a stronghold in Syria near the border with Turkey on Monday, four days after losing it to a grouping of rebels, a monitoring group claimed, as the group was battered by United States-led airstrikes over the weekend.
The ultra-hardline Islamist group seized the town of al-Rai from factions fighting under the banner of the Free Syrian Army, part of months of back-and-forth fighting in northern Aleppo province, the UK-based Syrian Observatory for Human Rights reported.
IS has made steady gains near the Azaz border crossing with Turkey since last May, but has been pushed back in a number of areas in recent months by rival rebels and Syrian government forces supported by Russian air strikes.
Meanwhile, the United States and its allies conducted 18 strikes against IS in Iraq and Syria on Sunday, the coalition leading the operations said.
In a statement released on Monday, the Combined Joint Task Force said five strikes in Syria, four of them near Mar'a, hit tactical units and destroyed fighting positions, vehicles, and a house-borne explosive device.
In Iraq, 13 strikes near six cities denied access to terrain and destroyed assembly areas, supply caches and a rocket rail, among other targets, the statement said.
Also on Sunday, the United Nations said it parachuted food supplies to thousands of people besieged by IS fighters in the Syrian city of Deir al-Zor on Sunday, in a bid to ease more than two years of blockades and shortages.
Many in the eastern city had been reduced to eating grass and wild vegetation, the UN World Food Program (WFP) reported.
The delivery of 26 pallets loaded with 20 tons of food came as one opposition official warned that a cessation of hostilities in Syria's civil war was on the verge of collapse.
International efforts to get in more aid also took a hit when Syria's government rejected UN requests last week to deliver aid to several towns besieged by its forces.
"The airdrop was the first time WFP food assistance has reached besieged parts of the city since March 2014," when the siege started, the WFP said in a statement.
More airdrops were planned in coming days and 22 of the pallets had already been picked up by Syrian Arab Red Crescent workers, it added.
Air drops are a last resort for delivering humanitarian aid because they are haphazard, expensive and can provide only a fraction of what can be supplied by a convoy of trucks. The surrounding Deir al-Zor province is important for IS, linking its de facto capital in Raqqa with its fighters in Iraq.