More food had finally started to reach famine-racked northern Gaza earlier this month, pushing down prices in the Jabalya refugee camp, where doctors like Yehia Abed were trying to save a legion of malnourished patients. Then came “another attack,” he said.

Israeli military operations this month against Hamas in Gaza — from the last, desperate refuge for Palestinians in the southern city of Rafah to the devastated refugee camps of the north — have displaced nearly a million people, according to the United Nations, and further sealed off the territory to outside aid. Aid groups say it has deepened the enclave’s humanitarian crisis and reversed their recent gains in staving off starvation and disease.