JERUSALEM — The killing of Hamas’s political leader, Ismail Haniyeh, on Wednesday upends cease-fire talks at a critical moment and, in the longer term, risks empowering more hard-line figures within the movement, according to experts and officials monitoring the group.

       Haniyeh was Hamas’s diplomat. He led its operations from exile in Qatar. Through 10 months of war, he was the group’s negotiator on the global stage, tasked with brokering a deal acceptable to the group in exchange for pausing fighting and releasing scores of Israeli hostages.