ISTANBUL — After a fight with his classmates, Wael al-Saud, a 9-year-old Syrian refugee, rushed to a local mosque to pray. Within hours, he was found hanging by his neck from a nearby cemetery gate.

Wael’s death earlier this month has stunned a country that shelters 3.6 million Syrians, more than any other country in the world, and where the government has spent tens of billions of dollars on the Syrians' education, health care and other programs aimed at integrating them into Turkish life during Syria’s protracted conflict.

But hostility toward refugees has mounted during a painful economic downturn. The fervor has even helped drive Turkey’s military incursion into northeast Syria, where President Recep Tayyip Erdogan has vowed to open up a “safe zone” to move up to 2 million Syrians. Other restrictive measures are already underway: On Wednesday, a deadline requiring refugees to return to provinces where they are registered or risk removal expired, threatening to uproot hundreds of thousands of people.

Yet experts and refugee advocates agree that Syria’s persistent sectarian strife and war-ravaged infrastructure mean most Syrians will be unable to return. For many in this “lost generation” of Syrians — the half-million children born here since the start of the war in 2011 — Turkey will likely remain home for years to come.