For years, Yacoub El Hillo, the top United Nations humanitarian official in Syria, has been warning that with the Syrian crisis — the “worst of our time” — the international system of humanitarian aid has “come to the breaking point,” especially as protracted conflicts pile up around the world, in Afghanistan, Iraq, Somalia and elsewhere.

“This is the price of political failure,” he said in Beirut in March, declaring that the breakdown of the aid system results from the strategic stalemate over Syria. “This is a direct affront to international peace and security.”

He said that it cost the United States $68,000 an hour to fly the warplanes used to battle the Islamic State, also known as ISIS or ISIL, while the United Nations has received less than half of the money it needs to take care of the half of Syria’s prewar population that has been displaced…

Few refugees have been accepted by the regional and global players that have helped fuel the conflict — not by the United States, Russia, Iran or the Gulf Arab states, some of which, despite their wealth, have pledged just tens of millions toward the billions of dollars Syrians need. Politics also intrudes on aid, with the combatants trying to restrict aid to areas held by their opponents.