Ismail Haniyeh, the political leader of Hamas, was killed by a strike in Tehran in the early hours of Wednesday morning, only hours after Israel said it had killed a top Hezbollah commander in Beirut.
The dual assassinations are heavy blows to Hamas and Hezbollah, but also raise the stakes for Iran, which backs both groups and vowed revenge. They will fuel growing fears that the war in Gaza could escalate into a broader regional conflict.
A senior Hamas official described Haniyeh’s killing as a “cowardly act that will not go unpunished”. Mediators Qatar and Egypt warned it would set back talks on a ceasefire and a deal to release hostages held in Gaza.
Haniyeh was targeted by an airstrike at a “residence in Tehran”, Hamas said, after he travelled to the Iranian capital for the inauguration of the country’s new president, Masoud Pezeshkian.
Iran’s supreme leader, Ayatollah Ali Khamenei, said that because the attack took place in Tehran, “we consider his revenge as our duty”. Pezeshkian said his country would defend its territorial integrity and honour, and make the “terrorist occupiers regret their cowardly action”.
The Israeli government officially declined to comment on Haniyeh’s death, but the strike was widely acknowledged as an Israeli operation both inside the country and beyond.
Israel vowed to kill all Hamas leaders after the 7 October attacks, and its intelligence services have a history of carrying out covert killings inside Iran, mostly targeting scientists working on the country’s nuclear programme.
The retired general Amos Yadlin, a former head of Israel’s Military Intelligence Directorate, described the attacks on Wednesday night as “two quality operations of Israel defence forces against two top terrorists, one in Beirut and one in Tehran”.
The US defence secretary, Lloyd Austin, speaking after the assassinations, said the Biden administration was “doing things to take the temperature down” but would come to Israel’s defence if it were attacked.
US officials have led a global months-long diplomatic effort to prevent the war in Gaza escalating into a broader regional conflict, but they now face an even steeper challenge.
Austin, who is visiting the Philippines, said he believed a wider conflagration could be avoided, despite the threat of revenge. “I don’t think war is inevitable. I maintain that,” he told reporters.
The senior Hamas official Moussa Abu Marzouk told a Hamas-run TV channel that Haniyeh’s killing was a “cowardly act that will not go unpunished”. Sami Abu Zuhri, another official, told Reuters it was “a grave escalation” that would not achieve its goals.
Hamas has survived past assassinations of its top leaders, including Haniyeh’s mentor Ahmed Yassin in 2004, and Haniyeh did not command operations on the ground in Gaza after leaving for exile in 2019.
Hamas fighters inside Gaza are led by Yahya Sinwar, thought to be the mastermind of the 7 October attacks in which about 1,200 people were killed and 250 were taken hostage.
The Biden administration has been pushing hard in recent months for at least a temporary ceasefire and hostage-release deal in Gaza, where the territory’s health authorities says nearly 40,000 Palestinians have been killed and more than 90,000 wounded since 8 October.
The US secretary of state, Antony Blinken, said on Wednesday that Washington had not been aware of or involved in Haniyeh’s assassination, and that a ceasefire deal for Gaza was still vital.
But negotiations are likely to be frozen after the attacks of recent days, and particularly after the killing of Haniyeh, who played a key role in talks from his Doha base. Qatar described the attack as a “dangerous escalation” that put ceasefire talks in jeopardy.
“How can mediation succeed when one party assassinates the negotiator on the other side?” the country’s prime minister, Sheikh Mohammed bin Abdulrahman Al Thani, wrote on X, joining a regional chorus of condemnation.
Russia and Turkey condemned Haniyeh’s assassination, with Moscow describing it as a “completely unacceptable political killing”, the Tass news agency reported.
Haniyeh’s funeral will be held in Iran on Thursday, and the country has declared three days of mourning. His body will then be flown to Doha for burial.
Haniyeh’s death came hours after Israel claimed it had killed Hezbollah’s top military commander, Fuad Shukur, in an airstrike on a south Beirut suburb launched in retaliation for a rocket attack that killed 12 children at the weekend.
Hezbollah confirmed on Wednesday that Shukur had been killed in the attack.
Lebanon’s foreign minister said the strike was a shock after assurances from Israel’s allies that the country planned a “limited response” that “would not produce a war”.
“That’s what we’re afraid of,” Abdallah Bou Habib told the Guardian. “We did not expect to be hit in Beirut. We thought these were red lines that the Israelis would respect.”
The Palestinian president, Mahmoud Abbas, condemned Haniyeh’s assassination, calling it a “cowardly act and dangerous development”.
Streets in Ramallah, where the Palestinian Authority is based, were empty after Palestinian national and Islamic factions called for a general strike and mass demonstrations.
Haniyeh had repeatedly urged Palestinians to be “steadfast” after Israel killed his mentor and members of his family. His own death is likely to elicit a similar response from other Hamas leaders.
After an airstrike killed three of his sons and four grandchildren in April he insisted in an interview with Al Jazeera that his personal loss would not prompt Hamas to shift its position in negotiations.
News of the assassinations was largely greeted with delight in Israel, as part completion of a promise to hunt down the men responsible for the 7 October atrocity.
Social media was filled with triumphant memes. The cabinet minister Amichai Chikli shared footage of Haniyeh apparently nodding to chants of “death to Israel”, with the caption “Careful what you wish for” in a post on X.
It was also seen as revindication for the security forces after the failures of 7 October. “It really revives a little bit of the lost dignity of the intelligence community of Israel,” said Tamir Hayman, a retired general who like Yadlin served as head of defence intelligence.
But the tactical impact of two complex strikes in the heart of regional capitals would not change Israel’s overall position, 10 months into its war in Gaza, he said.
“I’m not neglecting the importance of this, but in terms of the overall strategic posture of Israel and the complicated situation we are facing to stop the war and achieve all our goals, it really does not change a lot,” he said.
He called on the government to use its military advantage now to push for a ceasefire deal and the return of hostages, and then turn its attention to securing the northern border. “If we continue [relying] on those very good tactical achievements, we are basically in the same place we have been yesterday,” he said.
Sufian Taha contributed reporting
