The Iranian-backed Hamas terrorist group chose Yahya Sinwar, its top official in the Gaza Strip, as its new leader after the assassination last week of Ismail Haniyeh in Tehran, The Times of Israel reported Tuesday.

Unlike Haniyeh, who lived in exile in Qatar for years, Sinwar remained in Gaza. Haniyeh was in Iran to attend the inauguration of Iran's newly elected president, Masoud Pezeshkian. Iran was quick to blame Israel for Haniyeh's death, but the Jewish state has neither confirmed nor denied involvement.

As Hamas' leader in Gaza since 2017, Sinwar rarely appeared in public but kept an iron grip on Hamas' rule. He is widely considered the mastermind of Hamas' Oct. 7 terrorist attack that saw the massacre of at least 1,200 Israeli civilians, with about 250 taken hostage.

"The choice of Hamas to name him leader of the movement now puts Gaza front and center of, not just the events on the ground, but certainly of the dynamics in the Hamas movement," Nour Odeh, a Palestinian political analyst based in Ramallah, told Al Jazeera. "And it really sends a signal, as far as negotiations of a cease-fire is concerned, that Gaza calls the shots."

Sinwar has been in hiding as Israel has conducted its military operation in Gaza, with a goal of eradicating Hamas and rescuing the remaining hostages.

The IDF in February published a video, filmed Oct. 10, said to show Sinwar walking through a Gaza tunnel with several of his family members, The Times of Israel reported.

"The hunt for Sinwar will not stop until we catch him, dead or alive," IDF spokesman Daniel Hagari said after release of the footage.

Sinwar is one of three Hamas officials for whom the International Criminal Court issued an arrest warrant because of war crimes committed Oct. 7. The other two, Haniyeh and Mohammad Deif, Hamas' military chief, are dead. Israel Defense Forces confirmed Aug. 1, a day after Haniyeh's death, that Deif died last month in a Gaza strike.

"This is happening precisely when Hamas is in its worst shape ever in Gaza," Palestinian affairs analyst Ohad Hemo told The Times of Israel, as the IDF works to destroy the group's military and governance capabilities. "It's a highly significant move" by Hamas, "an expression of faith in the man who has been leading it in Gaza and, if I may so, into the abyss."

• Mohammed Deif, Hamas Military Leader Who Eluded Israel for Decades, Is Claimed to be Dead
• Iran: Short-Range Projectile Killed Hamas' Haniyeh