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President Joe Biden on Thursday said Yahya Sinwar's death is a “good day” for Israel, the US and the world, and creates an “opportunity” for a Gaza without Hamas.
Mr Biden spoke with Prime Minister Benjamin Netanyahu to "congratulate him on the mission conducted in Gaza that killed Hamas leader Yahya Sinwar", the White House said.
They "discussed how to use this moment to bring the hostages home and to bring the war to a close with Israel’s security assured and Hamas never again able to control Gaza".
Mr Sinwar, who became the leader of Hamas after the assassination of Ismail Haniyeh this year, was killed on Wednesday in an operation in southern Gaza “after a year-long pursuit”, according to the Israeli military.
Mr Biden said that shortly after the Hamas-led October 7 assaults on southern Israel, he had directed US intelligence forces to help the Israeli military find Mr Sinwar, who was considered to be the architect of the attacks.
The Pentagon said later that no US forces were directly involved in Mr Sinwar's killing.
The President said Mr Sinwar’s death now brings a chance for a “day after” in Gaza without Hamas in power, and for “a political settlement that provides a better future for Israelis and Palestinians alike”.
Vice President Kamala Harris commended US intelligence personnel for helping to track Mr Sinwar down and issued a warning to "terrorists" who threaten Americans or American interests: "Know this: we will always bring you to justice."
Ms Harris, who is running for president, repeated her commitment to Israel's self-defence and said she would "always work to create a future of peace, dignity and security for all".
National Security Adviser Jake Sullivan, who is accompanying Mr Biden on a trip to Germany to discuss the war in Ukraine, said Mr Sinwar's death marked “a very significant day in the Middle East”.
Mr Sullivan said that Mr Sinwar was a “critical figure” in all aspects of Hamas, who had consolidated control of the political and military wings of the group under his leadership, particularly in recent weeks and months.
“I think his removal from the battlefield does present an opportunity to find a way forward that gets the hostages home … and brings us to a day after. That's something we're going to have to talk about with our Israeli counterparts,” he told reporters on Air Force One.
Mr Biden and Mr Sullivan's comments echoed those of Mr Netanyahu, who acknowledged Sinwar's death as a victory. But Mr Netanyahu said “the task before us is not yet complete … the war is not over yet”.
State Department spokesman Matthew Miller said that the objective of releasing the hostages, seven of whom are Americans, remained. Mr Miller that although Hamas has been weakened, the group maintains "significant ability to wreak havoc and launch terrorist attacks".
"The path that Sinwar wanted for the region – death, destruction, instability, chaos – is a path that we know the people of the region will reject. The horrors of the past year cannot be the future," he said.
But Mr Miller added that: "Ultimately, we think the path forward is not just to continue military operations that they will have to repeat over and over again."
US Secretary of State Antony Blinken added in a statement that the US would "redouble its efforts with partners to end this conflict, secure the release of all hostages and chart a new path forward that will enable the people of Gaza to rebuild their lives and realise their aspirations free from war and free from the brutal grip of Hamas".
Representative Gregory Meeks, the top Democrat on the House Foreign Affairs Committee said that, with Mr Sinwar’s death, there is a "glimmer of hope amidst the regional war".
"Any Palestinian leader who follows in Sinwar’s ideological footsteps will only bring more suffering to the Palestinian people.," he added.
Israeli Defence Minister Yoav Gallant spoke to US Defence Secretary Lloyd Austin after the death of Mr Sinwar and talked about the firefight in which he was killed.
“Minister Gallant discussed the intense exchanges of fire between [Israeli] troops and Hamas terrorists in Gaza, which led to the elimination of several senior operatives, among them the leader of the organisation and planner of the October 7 massacre,” the Israeli government said.
The Pentagon did not immediately release its own report on the conversation, but in a statement Mr Austin said: “Our top and most urgent priority is to secure the release of each and every hostage, including our own American citizens.”
Patrick deHahn contributed to this report from New York