Hamas political chief Ismail Haniyeh assassinated in Tehran

CAIRO: Hamas leader Ismail Haniyeh was assassinated in the early hours of the morning in Iran, the Palestinian resistance group announced on Wednesday, raising fears of a wider escalation in a region already destabilized by Israel's assault on Gaza and a worsening conflict in Lebanon.

Iran's Revolutionary Guards confirmed Haniyeh's death hours after he attended a swearing-in ceremony for the country's new president and stated that an investigation was underway.

There was no immediate comment from Israel. The Israeli military indicated it was conducting a situational assessment but had not issued any new security guidelines for civilians.

US Defence Secretary Lloyd Austin stated that Washington would work to try to ease tensions but affirmed that the United States would help defend Israel if it were attacked.

The assassination, occurring less than 24 hours after Israel claimed to have killed a Hezbollah commander behind a deadly strike in the Israeli-occupied Golan Heights, appears to diminish the chances of an imminent ceasefire agreement in Gaza.

"This assassination by the Israeli occupation of Brother Haniyeh is a grave escalation that aims to break the will of Hamas," senior Hamas official Sami Abu Zuhri told Reuters. He added that Hamas would continue on its current path and expressed confidence in eventual victory.

A source with knowledge of the meeting stated that Iran's top security body is expected to convene to decide Iran's strategy in reaction to the death of Haniyeh, a close ally of Tehran.

Palestinian President Mahmoud Abbas condemned Haniyeh's killing, and Palestinian factions in the occupied West Bank called for a general strike and mass demonstrations.

Haniyeh, typically based in Qatar, has been the face of the Palestinian group's international diplomacy. The war, ignited by the Hamas-led attack on Israel on October 7, has raged in Gaza, where three of Haniyeh's sons were killed in an Israeli airstrike.

The International Criminal Court's prosecutor's office requested an arrest warrant for Haniyeh over alleged war crimes, alongside a similar request against Israeli Prime Minister Benjamin Netanyahu.

Appointed to Hamas's top position in 2017, Haniyeh has moved between Turkey and Qatar's capital, Doha, circumventing the travel restrictions of the blockaded Gaza Strip. This mobility enabled him to act as a negotiator in ceasefire talks and to maintain communications with Hamas' ally, Iran.

The assassination of Haniyeh comes as Israel's campaign in Gaza approaches its 10th month with no signs of an end to the conflict that has shaken the Middle East and threatened to escalate into a broader regional war.

Despite mounting international pressure for a ceasefire and criticism of Netanyahu's government from families of Israeli hostages still held in Gaza, talks brokered by Egypt and Qatar seem to have stalled.

Simultaneously, the risk of war between Israel and Hezbollah has grown following a strike in the Golan Heights that killed 12 children in a Druze village on Saturday and the subsequent killing of senior Hezbollah commander Fuad Shukr.