Israeli forces’ killing of Hamas leader Yahya Sinwar is a seismic event that could create a pathway to a ceasefire agreement. Hamas is still holding about a hundred hostages whom it kidnapped over a year ago during the Oct. 7, 2023, terrorist attacks that destabilized the region. Sinwar had been the obstacle blocking a ceasefire deal ending Israel’s war in Gaza in exchange for releasing those hostages, U.S. officials said last month. “We’re calling on the Israeli government and the U.S....