Israeli Prime Minister Benjamin Netanyahu and U.S. President Joe Biden agreed to jointly work for the release of hostages held in Gaza following the killing of Hamas chief Yahya Sinwar, the premier's office said.

After months of disappointment, U.S. President Joe Biden's administration sees new hope for reaching a Gaza ceasefire after Israel killed Hamas leader Yahya Sinwar, but the upcoming U.S. elections cast a shadow on prospects for a breakthrough.

U.S. President Joe Biden and European leaders meeting during his farewell visit to Germany on Friday were expected to renew calls for a Gaza ceasefire after Israel said it killed Hamas leader Yahya Sinwar.

Israel's killing of Yahya Sinwar, Hamas' top leader and the mastermind of the group's Oct. 7 attack, is a dramatic turning point in the brutal yearlong war that it touched off.

Sinwar's killing on Thursday decapitates the Palestinian militant group that has already been reeling from months of assassinations up and down its ranks. And it is a potent symbolic achievement for Israel in its battle to destroy Hamas.

Iran’s Mission to the United Nations has issued a statement honoring Yahya Sinwar, the leader of Hamas, after Israel said Thursday he had been killed in fighting:

“When U.S. forces dragged a disheveled Saddam Hussein out of an underground hole, he begged them not to kill him despite being armed. Those who regarded Saddam as their model of resistance eventually collapsed. However when Muslims look up to martyr Sinwar standing on the battlefield — in combat attire and out in the open, not in a hideout, facing the enemy — the spirit of resistance will be strengthened. He will become a model for the youth and children who will carry forth his path for the liberation of Palestine. As long as occupation and aggression exist, resistance will endure, for the martyr remains alive and a source of inspiration.”

Prime Minister Benjamin Netanyahu said Israel has “settled its account” with “the person who carried out the worst massacre in the history of our people since the Holocaust.”

Netanyahu addressed the families of the hostages Thursday saying it was an “important moment in the war” to bring home the hostages. He also said anyone who surrendered weapons and assisted with the return of the hostages would be allowed to leave Gaza safely.

Yahya Sinwar masterminded an attack on Israel that shocked the world, unleashing a still-widening catastrophe with no end in sight.

In Gaza, no figure loomed larger in determining the war's trajectory than the 61-year-old Hamas leader. Obsessive, disciplined and dictatorial, he was a rarely seen veteran militant who learned Hebrew over years spent in Israeli prisons and who carefully studied his enemy.

Israel's President Isaac Herzog on Thursday called for swift action to bring back hostages held in Gaza, as he hailed the killing of Hamas leader Yahya Sinwar by Israeli forces.

Herzog on social media platform X said the slain Hamas chief was the mastermind of the October 7, 2023 attack that triggered the ongoing war and "has for years been responsible for heinous acts of terrorism against Israeli civilians", also calling on Israeli leaders to "act in every way possible to bring back" the remaining hostages.

The Disasters Emergency Committee (DEC) is launching a Middle East Humanitarian Appeal to raise urgent funds for people whose lives are being devastated by conflict.

"Over the past year, conflict in the Middle East has devastated lives across the region, and millions have fled their homes in search of safety. Right now, millions of people across Gaza, Lebanon and the wider region are in urgent need of food, shelter and medical care," DEC said in a statement.

Israeli forces in Gaza killed Hamas' top leader Yahya Sinwar, a chief architect of last year's attack on Israel that sparked the war, the military said Thursday. Troops appeared to have run across him in a battle, only to discover afterwards that a body in the rubble was the man Israel has hunted for more than a year.

Sinwar has topped Israel's most wanted list since the beginning of the Israel-Hamas war just over a year ago, and his killing strikes a powerful blow to the militant group. There was no immediate confirmation from Hamas of his death.