The head of the Palestinian resistance movement Hamas, Ismail Haniyeh, was assassinated by Israel in the Iranian capital Tehran, the group confirmed Wednesday.
Iran's Revolutionary Guards confirmed the death of Haniyeh, hours after he attended a swearing-in ceremony for the country's new president, and said it was investigating.
"The residence of Ismail Haniyeh, head of the political office of Hamas Islamic Resistance, was hit in Tehran, and as a result of this incident, him and one of his bodyguards were martyred," said a statement by the Islamic Revolutionary Guard Corps's Sepah news website.
Hamas announced that Haniyeh was killed in an Israeli raid on his residence in Tehran.
"Brother, leader, mujahid Ismail Haniyeh, the head of the movement, died in a Zionist strike on his headquarters in Tehran after he participated in the inauguration of the new (Iranian) president," the movement said in a statement.
Calling Haniyeh's assassination a "cowardly act," Hamas vowed to take revenge from Israel.
There was no immediate comment from Israel. The Israeli military said it was conducting a situational assessment but had not issued any new security guidelines for civilians. Prime Minister Benjamin Netanyahu met with security officials for consultations at midday.
The news, which came less than 24 hours after Israel claimed to have killed the Hezbollah commander it said was behind a deadly strike in the Israeli-occupied Golan Heights, appears to set back chances of any imminent cease-fire agreement in Gaza.
Qatar, which has been brokering talks aimed at halting the fighting in Gaza, condemned Haniyeh's killing as a dangerous escalation of the conflict. China and Russia have also condemned the assassination.
Iran's top security body met to decide Iran's strategy in reaction to the death of Haniyeh, a close ally of Tehran, in the Iranian capital, said a source with knowledge of the situation.
The assassination of Haniyeh comes as Israel's genocidal war on Gaza approaches the end of its 10th month with no sign of an end to a conflict that has shaken the Middle East and threatened to spiral into a wider regional conflict.
Despite anger at Netanyahu's government from families of the Israeli hostages still held in Gaza and mounting international pressure for a cease-fire, talks brokered by Egypt and Qatar appear to have faltered.
Appointed to the Hamas top job in 2017, Haniyeh moved between Türkiye and Qatar's capital Doha, escaping the travel curbs of the blockaded Gaza Strip and enabling him to act as a negotiator in cease-fire talks or to talk to Hamas' ally Iran.
His death, following the killing of his deputy Saleh Al-Arouri earlier this year by Israel, leaves Yehya al-Sinwar, the Hamas chief in the Gaza Strip and the alleged architect of the Oct. 7 incursion, and Zaher Jabarin, the head of the group in the West Bank, in place but in hiding.
Further ahead, Khaled Meshaal, the group's former chief, has emerged as a potential replacement as the public face of Hamas, but it remains unclear how the succession will be handled.
The war was triggered by the Oct. 7 incursion that caused 1,200 deaths and the abduction of some 250 hostages into Gaza, by Israeli tallies.
In response, Israel launched a brutal ground and air offensive in the densely populated coastal enclave that has killed more than 39,400 people, according to Gaza health officials, and left more than 2 million facing a severe humanitarian crisis.
