As Syria’s crisis moves into its third year, international relief agencies are expressing alarm at the slow arrival and modest levels of financial support they are receiving to help the tens of thousands of civilians who have been fleeing the conflict and the millions trapped inside the country whose plight becomes more desperate.

Halfway into an appeal for $1.5 billion to cover the cost of aid to Syrians in the first six month of the year, United Nations officials say they have received barely one-fifth of the money. “That math just doesn’t work,” said Radhouane Nouicer, the United Nations’s regional humanitarian coordinator, in a statement from the Jordanian capital, Amman, on Friday. “It translates into less food, fewer blankets, fewer medicines, less clean water.”