Israeli officials believe Mohammed Sinwar, the younger brother of Yahya Sinwar who was killed on Wednesday, could be the next leader of Hamas, according to multiple Israeli media outlets.

The Israel Defense Forces (IDF) could not be immediately reached for comment on the possible next head of the terrorist organization in Gaza, but according to Israeli media citing the IDF, Mohammed Sinwar is expected to assume political leadership of Hamas.

Mohammed Sinwar, born in 1975, is 13 years younger than his brother. He was born in the Khan Younis refugee camp, where his family had been displaced during the 1948 Arab-Israeli War.

Growing up under the influence of his brother, one of the founders of Hamas, and witnessing his brother’s arrest in 1991 for suspected terrorist activities, Mohammed Sinwar developed close ties with high-ranking Hamas officials.

While the public knows relatively little about Mohammed Sinwar, his operational experience in Hamas allegedly made him one of the IDF’s top targets within the group.

“You won’t find a key event in Hamas’s military buildup over the past 25 years in which Mohammed Sinwar wasn’t involved,” a military source said.

Israeli security officials reportedly said that Mohammed Sinwar is considered even more ruthless than his older brother. They described him as an “arch-terrorist” and pointed to his direct involvement in the torture and deaths of Palestinians in Gaza to gain information about the IDF and Shin Bet, Israel’s security agency.

“No one in Hamas understands Israel’s covert operational patterns better than him. He conducted all the interrogations himself, learning everything from start to finish,” one official told the media outlet.

Despite concerns about the ruthless tendencies of the expected new Hamas leader, U.S. Secretary of Defense Lloyd Austin said on Friday that Yahya Sinwar’s death could be an “extraordinary opportunity to achieve a lasting ceasefire.”

“We’ll see how things evolve,” he said from a NATO summit in Brussels when asked about Israeli Prime Minister Benjamin Netanyahu’s vow to continue fighting in Gaza. “But clearly there are opportunities for a change in direction, and we would hope that, you know, parties would take advantage of that, both in Lebanon [and] in Gaza.”

Despite Austin’s optimistic tone and a meeting reportedly scheduled for Friday by Netanyahu to discuss the 101 hostages still held in Gaza, Hamas has stated that the hostages will not be exchanged until .

Israeli reports also suggested that the IDF believes the threat posed by Hamas will not be effectively eliminated until Hamas’s hierarchical structure is dismantled.

While Mohammed Sinwar is expected to take over as the next leader of Hamas, the presence of other top officials in the terrorist organization means that the group remains a threat.

Khalil Al-Hayya, who led the indirect ceasefire talks between Hamas and Israel and was reportedly in Tehran when longtime Hamas leader Ismail Haniyeh was killed in July, also served as Yahya Sinwar’s deputy and is believed to remain a major player in the terrorist organization.

Khaled Meshaal, who led Hamas between 2004 and 2017 and now resides in Qatar according to Reuters, was listed as a potential successor following the assassination of Haniyeh. It was suggested that Yahya Sinwar opposed his reappointment to the top job.

Mahmoud al-Zahar, a senior Hamas official and one of the group’s founders, was also considered a candidate for the top job after Yahya Sinwar’s death. He reportedly survived two assassination attempts in 1992 and 2003, though Reuters has said that he has not been seen since the October 7, 2023 attacks.

Mohammad Shabana remains one of the most senior veteran commanders in the terrorist groups and reportedly heads a battalion in Rafah. He also played a key role in developing the tunnels used to attack Israel during the 2006 conflict.

Several other officials were mentioned as top Hamas officials who would be crucial in dismantling the terrorist network, though neither their whereabouts nor their deaths have been officially confirmed by Hamas.