The United Nations said it airdropped food supplies to thousands of people besieged by ISIS militants in the Syrian city of Deir al-Zor on Sunday.

The delivery of 26 pallets loaded with 20 tons of food is an attempt to ease blockades and shortages Syrian citizens have been living with for more than more than two years.

“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.

Many in the eastern city had been reduced to eating grass and wild vegetation, the U.N. World Food Programme (WFP) reported.

The step 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 U.N. requests last week to deliver aid to several towns besieged by its forces.

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.

Organizations resort to air drops to deliver humanitarian aid as a last option, given that 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 pivotal for ISIS, linking its de facto capital in Raqqa with its fighters in Iraq.