More than a year after Hamas’ devastating October 7 attacks on Israel, the country’s military said Thursday it had killed the man it considers to have been the chief architect of that cross-border incursion – raising questions about the future of the war and of the militant group itself,

In confirming Sinwar’s death — a full day after it was announced by Israel — Hamas said Friday it mourned the loss of a “great leader.” But it voiced defiance, vowing not to return the hostages seized on Oct. 7 of last year to Israel until there is a ceasefire in the Gaza Strip and a withdrawal of Israeli troops.

U.S. officials said that senior White House officials regularly met with William J. Burns, the C.I.A. director, and Lloyd J. Austin III, the defense secretary, about what more support the targeting cells might need to speed the hunt for Mr. Sinwar.