Yahya Sinwar, the leader of the U.S.- and EU-designated Palestinian terrorist group Hamas, is dead, according to Israel.
Foreign Minister Israel Katz announced on October 17 that Sinwar was killed during a military operation in the Gaza Strip. Hamas has not yet commented.
The 62-year-old was the alleged architect of the deadly October 7, 2023, attack on Israel. The unprecedented assault triggered Israel's ongoing war in the Palestinian enclave.
Sinwar became Hamas's top leader soon after Israel's suspected assassination of Ismail Haniyeh, the group's political chief, in Tehran on July 31.
Sinwar, the head of Hamas's military wing, the Izz al-Din al-Qassam Brigades, was not considered the favorite to succeed Haniyeh, who lived in Qatar.
Khaled Meshaal, a former political chief of Hamas, and Khalil al-Hayya, a prominent figure within the political wing, were seen as frontrunners.
Traditionally, Hamas's political chief is based abroad so he can travel and maintain contact with regional allies, such as Iran and Hezbollah. Sinwar is believed to be in Gaza.
A key reason for Sinwar's appointment, experts said, was his close ties with Iran, which has provided financial and military support to the group.
Yahya Sinwar waves to supporters during a rally in the Gaza Strip in April 2023.
Molded By Israeli Prisons
Also known by his supporters as Abu Ibrahim, Sinwar was born in a refugee camp in the city of Khan Younis in Gaza.
His parents, like Haniyeh's, fled the coastal town of Ashkelon during the 1948 Arab-Israeli War that resulted in the establishment of the state of Israel -- or what Palestinians call the "nakba," or catastrophe.
Sinwar joined Hamas shortly after it was formed in 1987 and set up its feared internal security organization, Al-Majd, whose main purpose was to find Israeli spies within the group. He gained a reputation for violence and was nicknamed the "Butcher of Khan Younis."
Sinwar was captured by Israeli forces and sentenced to multiple life terms for a variety of offenses -- including the killing of two Israeli soldiers -- and spent more than two decades in prison.
While in prison, Sinwar organized strikes to improve working conditions and emerged as a leader among incarcerated Palestinians.
Sinwar was released from prison in 2011 as part of an exchange that saw more than 1,000 Palestinian prisoners freed in return for one Israeli soldier held by Hamas.
Soon after his release, Sinwar accompanied Haniyeh on a trip to Tehran, where he met Supreme Leader Ayatollah Ali Khamenei.