Rushdi Abualouf
Gaza correspondent

This morning I spoke to three senior Hamas officials, and they were all in a state of shock.

They gave different - quite confusing - accounts as to what exactly happened in the Iranian capital, Tehran, in the early hours of today.

They said they were very surprised by the attack, that Haniyeh had visited the city many times before and must have felt safe going there.

And the question now arises as to who should be responsible for this major security failure - and was it the right decision for Haniyeh to be in Tehran in the first place?

Jaroslav Lukiv
Live reporter

Image source, EPA

It's coming up to eight hours since news first broke of Haniyeh's death - and reaction is still coming in. Here's what's been happening:

• Ismail Haniyeh killed: Hamas says its political leader was killed in an Israeli attack in Iran's capital Tehran early on Wednesday - more on who he was here
• What happened? According to Iranian state media, an air strike hit a building for war veterans in Tehran where Haniyeh was staying at around 02:00 local time
• Who is responsible? Israel has been blamed but is yet respond to the accusations. It has previously vowed to eliminate Hamas's leaders following the group's 7 October attack
• Iran vows revenge: Iran's president - Hamas's most important backer - promises to avenge Haniyeh's death
• Condemnation: There has been widespread criticism of the attack from across the Middle East, amid fears of further escalation. (Will things escalate? Our security correspondent gives his take)
• Ceasefire talks: And there are also concerns for what it means for ceasefire talks - as Haniyeh was a key figure in negotiations. Qatar's PM says how can talks succeed when one side targets another
• Elsewhere: The attack in Tehran comes hours after Israel claimed it killed a senior commander of the powerful Hezbollah militant group in Lebanon. Hezbollah confirmed the strike happened - but says it's still searching rubble for the commander

Frank Gardner
Security correspondent

Clearly this an extremely dangerous moment for the Middle East.

Iran has vowed revenge and the last time that happened it sent a barrage of hundreds of missiles and drones at Israel, which then responded with a calibrated missile attack close to Iran’s nuclear facilities. It took frantic diplomatic intervention to dissuade Israel from hitting harder.

But not every incident like this leads to escalation.

In 2020 then-President Trump ordered the assassination of Iran’s most powerful military commander Gen Qasem Soleimani, in Baghdad.

There were furious calls for revenge but not much happened.

In 1986, then-President Reagan ordered an airstrike on Libya in retaliation for the bombing of a Berlin discotheque.

There were fears the Arab world would erupt in flames but it didn’t.

This time though, there are many more parties involved: a seemingly endless Israeli operation in Gaza; Hezbollah in Lebanon wounded by the assassination of a commander; the Houthis in Yemen vowing revenge for an Israeli airstrike; and Iran humiliated by a missile strike on a guest right in the heart of its capital.

We're just hearing a bit more from US Secretary of State Antony Blinken.

"This is something we were not aware of or involved in," he says.

Image source, Getty Images

More now on what's at stake for ceasefire talks.

US Secretary of State Antony Blinken says he won't speculate on what impact today's news might have - but he stresses the importance of continuing to push for a ceasefire.

"Nothing takes away from the importance of getting to the ceasefire, which is manifestly in the interest of the hostages and bringing them home," he says during an event in Singapore.

Blinken says Palestinians "are suffering terribly every single day, children, women, men in Gaza caught in this crossfire that Hamas is making".

Rushdi Abualouf
Gaza correspondent

As we've just reported, Haniyeh's killing may also have a wider impact on the ongoing efforts to end the Israel-Hamas war.

In December, Hamas briefly suspended ceasefire talks with Israel following the killing of Haniyeh's deputy in the Lebanese capital, Beirut.

And this latest attack in Tehran could make it harder to reach a truce as Hamas will now be focused more on finding Haniyeh's successor in what could be a complicated and prolonged process.

Qatar - which has been brokering ceasefire talks between Hamas and Israel - has suggested Haniyeh's killing could jeopardise the talks. Haniyeh played a significant role in the negotiations.

"Political assassinations and continued targeting of civilians in Gaza while talks continue lead us to ask, how can mediation succeed when one party assassinates the negotiator on other side?" Qatar's PM says.

"Peace needs serious partners and a global stance against the disregard for human life."

Israel has not responded to claims that it's behind the attack.

Hugo Bachega
Middle East correspondent, in Beirut

Away from Haniyeh’s death for a moment, I'm here in Beirut near to where Israel struck a building in a Hezbollah stronghold yesterday. They claimed to have killed a senior commander, Fuad Shukr.

The area in Dahiya in the city’s southern suburbs has been cordoned off, and there is a heavy presence of members of the group and soldiers from the Lebanese army.

Shops are closed and emergency services are still searching through the rubble of the building hit.

It is believed that this is the first time Hezbollah has been targeted in its stronghold in Beirut, but this area was hit before in the current crisis - in January, an attack killed a top Hamas official.

In a statement this morning, Hezbollah says the senior commander targeted was in the building when the attack happened yesterday, just before sunset, but did not confirm he was killed, as announced by the Israeli military.

We still do not know how Hezbollah will respond but a retaliation is all but certain.

Jeremy Bowen
International editor

I first met Ismail Haniyeh back in the late 1990s, when he was a rising Hamas official in Gaza.

His family has already been targeted by Israel since 7 October - sons and grandchildren who were travelling with him, killed by the Israelis.

What is interesting about this is that Haniyeh was not a figure that lived in hiding, like the leaders of the military wing.

Assuming it was Israel who killed him, and I can’t say who else it might be - and they haven’t commented as yet - why are they doing it now when they must have had some chances in the past?

It was not politically possible for them to kill him in Qatar. Killing him in Iran though, does send a message about Israel’s reach, a message that no one is safe.

Haniyeh was involved in the ceasefire and hostage release talks, so this is not going to make those any easier.

Haniyeh had been in Iran to attend the inauguration of new President Masoud Pezeshkian, who was elected earlier this month.

He was usually based between Qatar and Turkey.

The reaction is continuing to come in from the region and beyond.

Jordan says it condemns "in the strongest terms Israel's assassination" of the Hamas leader - and that it will lead to "more tension and chaos in the region".

A reminder - Israel has not commented on whether it was behind the attack.

It was also condemned by Lebanon - whose Prime Minister Najib Mikati also warned of a serious escalation in the wider region at an urgent meeting of his cabinet this morning.

And China's foreign ministry says it "resolutely opposes and condemns the assassination" and is "deeply concerned" about more turbulence in the region.

Spokesman Lin Jian adds "a comprehensive and permanent ceasefire" should be reached in Gaza.

Raffi Berg
Middle East online editor

The killing of the overall leader of Hamas is seismic in terms of both the target and where it happened.

Weeks after the unprecedented 7 October attack by Hamas on Israel, Israeli Prime Minister Benjamin Netanyahu said publicly that he had instructed the Mossad – Israel’s intelligence agency – “to act against the Hamas leaders wherever they are”.

Ismail Haniyeh was in Tehran when he was killed, reportedly by an aerial strike.

The fact that it happened not in Qatar where Haniyeh lived surrounded by security, but inside Iran – Hamas’s most important backer – sends a signal that nowhere is off-limits if it is indeed confirmed that Israel carried out the strike, and that it is capable and willing of acting right under the nose of its most mortal foe.

Haniyeh’s death comes just two weeks after Israel targeted Hamas’s number two, its elusive military chief Mohammed Deif, in Gaza. Indications are that he was killed.

The removal of Hamas’s top political and military leaders is the biggest blow to the group on an individual and operational level since the war began.

Iranian President Masoud Pezeshkian says he will make Israel "regret" the "cowardly" killing of Haniyeh, adding that Iran would "defend its territorial integrity, honour pride and dignity".

In a statement quoted by AFP news agency, the Iranian president described Haniyeh as a "brave leader".

The Hamas political leader, who is based in Qatar, was visiting Tehran to attend Pezeshkian's presidential inauguration ceremony.

Iran's supreme leader, Ayatollah Ali Khamenei also says that avenging his death is "Tehran's duty", adding that Israel - who has not claimed responsibility - had provided the grounds for "harsh punishment".

Image source, Reuters

Paul Adams
Diplomatic correspondent, reporting from Jerusalem

While details of the attack slowly emerge, its political consequences are also coming into focus.

The most obvious is the likely damage to fragile efforts to negotiate a ceasefire in Gaza.

Ismail Haniyeh may not have been in charge of day-to-day events on the ground in Gaza - that’s the domain of the military commander Yahya Sinwar - but as the Hamas leader in exile he was a critical interlocutor in negotiations brokered by Qatar, the US and Egypt.

American officials had recently suggested that ceasefire negotiations might soon succeed, although a meeting in Rome last weekend did not result in a breakthrough.

But it’s extremely hard to see how any progress can be made in the immediate wake of the assassination of Haniyeh.

All of which begs the question: if this was, as everyone assumes, an Israeli operation, why was it carried out?

Beyond the desire to exact revenge on anyone associated with Hamas, what was Israel hoping to achieve?

Turkey’s foreign ministry has already summed up the likely reaction of many in the region - accusing Benjamin Netanyahu of having "no intention of achieving peace".

We're still getting more reaction coming in to Haniyeh's death.

In a statement, Qatar's foreign ministry described it as a "heinous crime, a dangerous escalation and a flagrant violation of international and humanitarian law".

It warned that "this assassination and the reckless Israeli behaviour of continuously targeting civilians will lead to the region slipping into chaos and undermine the chances of peace".

Israel hasn't yet responded to the death.

Paul Adams
Diplomatic correspondent

We’re beginning to get some idea of how Ismail Haniyeh was killed. Early indications suggest that he and his bodyguard died when a rocket hit the house where he was staying.

All eyes will inevitably fall on Israel, which vowed to hunt down and punish all Hamas leaders following the brutal attacks of 7 October, in which around 1,200 Israelis and foreigners were killed.

Israel typically doesn’t comment on its operations abroad, but this attack may have followed the same pattern as an Israeli operation which targeted Iranian air defences around its nuclear facility in Natanz on 19 April.

In that operation, Israeli jets are believed to have fired rockets from outside Iranian airspace.

The BBC's Middle East correspondent Yolande Knell says until now Israel has mostly failed to get to the top of its most wanted list.

She says this attack would have been "extremely well planned." You can watch the latest from her here:

Rushdi Abualouf
BBC News Gaza correspondent

Now we have to wait and see how Hamas will react.

We will see who will win: a more pragmatic leader, or a more extremist leader in Gaza.

One senior Hamas official has told me: “Hamas is an idea, Hamas is an ideology. And the killing of the leader will not change Hamas, and will not make Hamas surrender or make any more concessions."

Lord Peter Ricketts, the UK's former national security adviser, says Haniyeh's assassination is "a very powerful demonstration of Israel's ability to reach out right across the region".

Israel hasn't responded to the attack, although has previously said it wants to eliminate Hamas's leaders.

Ricketts says it gives Israel the "political room to begin now to wind down the operation in Gaza because [Netanyahu] can now say he has really delivered a major blow against Haniyeh's leadership".

But Ricketts says it "remains a very dangerous time in the Middle East" as Hamas is now unlikely to want to settle in ceasefire talks.

Sebastian Usher
Middle East analyst

Image source, EPA

Born in a refugee camp in Gaza in 1963, Ismail Haniyeh was a key member of Hamas from its inception.

He was imprisoned by Israel a number of times and at one point was expelled to south Lebanon for six months.

In 2003, he survived an assassination attempt by Israel, along with Hamas's founder.

Three years later, he was briefly Palestinian prime minister after Hamas won elections - but a violent rift between Hamas and the other main Palestinian faction, Fatah, followed a year later.

Widely regarded as a pragmatist, Haniyeh was said to have maintained good relations with other rival Palestinian groups.

He was elected head of Hamas’s political bureau in 2017. In recent years, he lived in exile, moving between Turkey and Qatar.

He had been playing a key role in negotiations over a ceasefire deal in Gaza.