Inside a lavish clubhouse on Doha's waterfront, tensions strained by months of fruitless back-and-forth weighed on negotiators as the hour neared 3 a.m.

On the first floor, a Hamas delegation whose leader had once evaded an Israeli airstrike that killed seven family members combed through the details of yet another proposal to halt the war in Gaza. On the second floor, advisers to Israel's intelligence chief, who had vowed to hunt down those responsible for the Oct. 7, 2023, attack that ignited the war, did the same.