Yahya Sinwar is dead. What we know about death of Hamas leader behind Oct. 7 attacks

This story has been updated with new information.

Yahya Sinwar , the elusive leader of Hamas regarded as the mastermind behind the militant group’s brutal attack on Israel last year, is dead.

Israel said Thursday it killed Sinwar during a military operation in Gaza.

Hamas has yet to comment, and it was not immediately clear what impact Sinwar’s death will have on the Israel-Hamas war.

Here’s what we know:

What's the latest on the death of Hamas leader Yahya Sinwar?

Israel’s Defense Forces announced it had killed three Hamas militants during a military operation in Gaza on Thursday and was investigating whether one of them was Sinwar.

A U.S. official who spoke on the condition of anonymity said Israel was conducting DNA tests on the victim’s body to determine if it was Sinwar.

Israel's Foreign Minister Israel Katz later confirmed Sinwar’s death.

"This is a significant and moral achievement for Israel and a victory for the entire free world against the axis of evil of radical Islam led by Iran," Katz said in a statement.

A second U.S. official, also speaking on the condition of anonymity, said it appears Sinwar may have been killed in a mortar attack.

Katz said Sinwar's death "opens the possibility" for the immediate release of the remaining hostages taken during Hamas' attack on Israel last year and "paves the way for a change that will lead to a new reality in Gaza."

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Who is Yahya Sinwar?

Sinwar was the leader of Hamas, which staged a surprise attack on Israe l on Oct. 7, 2023, killing 1,200 people and taking 250 hostages . He was considered one of the architects of the attack, which touched off a bloody war between Israel and Hamas that, according to the Hamas-run Gaza Health Ministry, has resulted in the deaths of more than 42,000 Palestinians.

Sinwar, 61, had been in charge of daily operations in Gaza before the Hamas’ Oct. 7 attack. He was declared Hamas’ political leader after his predecessor, Ismail Haniyeh , was killed in July by a bomb hidden in his guesthouse in Tehran.

Dubbed "The Face of Evil" by Israel, Sinwar was known for operating in secrecy, moving constantly and using trusted messengers for non-digital communication, three Hamas officials and one regional official told Reuters. He had not been seen in public since the Oct. 7 attack on Israel and was believed to be hiding in the network of tunnels that Hamas used to conceal weapons, fighters and hostages.

Sinwar was a key player in failed negotiations for a ceasefire and hostage-release deal. He was the sole decision-maker for Hamas, three Hamas sources told Reuters. Negotiators would wait for days for responses filtered through a secretive chain of messengers.

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Sinwar's early years

Sinwar was born in the Khan Younis refugee camp in southern Gaza in 1962. Before the war, he would sometimes tell of his early life in Gaza during decades of Israeli occupation. He once said his mother made clothes from empty U.N. food-aid sacks, Gaza resident Wissam Ibrahim, told Reuters.

In a semi-autobiographical novel written in prison, Sinwar described scenes of troops bulldozing Palestinian houses, "like a monster crushing its prey’s bones," before Israel withdrew from Gaza in 2005.

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A ruthless enforcer tasked with punishing Palestinians suspected of informing for Israel, Sinwar then made his name as a prison leader, emerging as a street hero from a 22-year Israeli sentence for masterminding the abduction and murder of two Israeli soldiers and four Palestinians. He then quickly rose to the top of the Hamas ranks.

He became a member of Hamas soon after its founding in the 1980s, adopting the group's radical Islamist ideology, which seeks to establish an Islamic state in historic Palestine and opposes Israel's existence.

He was arrested by Israel in the late 1980s for allegedly orchestrating the killing of two Israel soldiers and several other Palestinians he accused of being collaborators. He was sentenced to four life sentences by Israel and had spent more of his life in jail than outside it when he released in a prisoner swap in 2011 that freed Gilad Shalit, an Israeli solider held captive by Hamas for five years.

Sinwar is believed to have helped establish Hamas' internal security service, known as Majd, whose tasks include finding and executing alleged Palestinian collaborators.

Sinwar was 'murderous terrorist' and 'obstacle' in ceasefire talks

White House National Security Adviser Jake Sullivan, traveling with President Joe Biden to Germany, called the news of Sinwar’s death a “very significant day in the Middle East.”

“This is a murderous terrorist responsible for the worst massacre of Jews since the Holocaust,” Sullivan told reporters aboard Air Force One. “He has a lot of blood on his hands – Israeli blood, American blood, Palestinian blood. And the world is better now that he's gone.”

Sinwar was “a massive obstacle" to peace in Gaza and efforts to secure a ceasefire and hostage-release deal, Sullivan said.

“At various points along the way, Sinwar was more interested in causing mayhem and chaos and death than actually trying to achieve a ceasefire and hostage deal,” Sullivan said. “We repeatedly saw a moment where it was him, in particular, who stood in the way of making progress towards the ceasefire-hostage deal.”

With his death, the U.S. will redouble its efforts to end the war, secure the release of the remaining hostages and chart a path forward that will enable the people of Gaza "to rebuild their lives and realize their aspirations free from war and free from the brutal grip of Hamas,” Secretary of State Antony Blinken said.

Contributing: Reuters; Kim Hjelmgaard and Tom Vanden Brook of USA TODAY.

Michael Collins covers the White House. Follow him on X @mcollinsNEWS.

This article originally appeared on USA TODAY: Yahya Sinwar is dead. What we know about death of Hamas leader behind Oct. 7 attacks