Iran reels after Hamas leader assassinated in heart of Tehran

A protester in Tehran holds up a picture of killed Hamas leader Ismail Haniyeh

The killing of Hamas’s political leader Ismail Haniyeh in Tehran represents a major escalation in the tensions between Iran and Israel.

Iran’s supreme leader Ayatollah Khamenei has blamed Israel for the air strike, and said the killing required “a harsh punishment”.

He added that it was Iran's "duty to avenge his blood".

The country's new president Masoud Pezeshkian echoed this sentiment, saying: “We will make the occupying terrorist regime regret its action.”

Israel has yet to respond but has previously vowed to eliminate Hamas's leaders following the 7 October attack launched by the group.

Iran has confirmed Mr Haniyeh and his bodyguard were killed at a guest house in northern Tehran at 02:00 local time by a missile fired from beyond Iran’s borders.

The immediate concern now is Iran’s response - what shape it might take and whether it would inflame tensions in the region, which are already at an all-time high.

In a post on X, formerly Twitter, Iran's mission to the UN said the response to the strike would be comprised of "special operations", which would be "harder and intended to instil deep regret to the perpetrator".

In April, Iran fired more than 300 missiles and drones at Israel in reaction to the killing of seven of its officers - including a top commander of its Quds Force - in the Syrian capital Damascus.

The action was unprecedented in its scope and seriousness, although Israel - together with the US and a number of regional and international partners - managed to destroy almost all the Iranian missiles and drones.

Iran launched a missile attack on Israel in April

It’s thought Iran could now unleash an attack of a similar kind on Israel. Tehran could also ask its proxy militias in the region to step up their attacks.

Lebanon's Hezbollah already has a reason of its own to escalate its cross-border missile war with Israel. The assassination of Mr Haniyeh came only a few hours after the killing of one of the group's own senior military commanders in southern Beirut.

Already there are commentators in the region who believe the tensions between Israel and Hezbollah could themselves spark a full-scale war.

The strike happened on a significant day for Iran's leaders. Mr Haniyeh was in the Iranian capital to take part in the swearing-in of newly elected president Masoud Pezeshkian.

He was among invited guests at the inauguration ceremony, alongside the leaders of some of Tehran's key allies.

The leader of the Palestinian Islamic Jihad group, Hezbollah's second-in-command, and a leader from Yemen’s Houthi group were all also front row guests at the ceremony. All received a warm welcome from Ayatollah Khamenei.

In his statement on Haniyeh's death, Iran's supreme leader said Israel had "martyred our dear guest in our house".

Mr Pezeshkian has reacted to the killing on X, saying that while yesterday he was raising his hand in parliament, today he has to shoulder Mr Haniyeh’s coffin.

Masoud Pezeshkian was sworn in as Iran's new president yesterday

The new Iranian president is viewed as a relatively moderate figure, who has spoken previously about mending relations with the West through dialogue, and putting Iran back on the map as a responsible member of the international community.

However, Mr Pezeshkian will be under pressure to take a hard line on Israel and to support Iran’s proxy militias in the region.

But ultimately, it is the supreme leader and the Revolutionary Guard that will decide on regional policies and Iran's response.

Reports from Tehran say the country’s national security council has held an emergency meeting at Ayatollah Khamenei's residence. What has been decided has not been made public, but the shape and timing of Iran's response are the questions most likely to have been discussed.

Iran may decide to move quickly, given that the targeted killing is a major loss of face for Tehran.

Does this make all-out war in the region more likely? It is difficult to say. Nobody appears to want such an outcome at the moment, but wars are not always the result of calculated risks.