The killing of Ismail Haniyeh, Hamas chief, came less than 24 hours after Israel claimed to have killed a Hezbollah commander who it said, was behind a deadly strike in the Israeli-occupied Golan Heights.
It appears to set back chances of any imminent ceasefire agreement in the Gaza war.
At the same time, the risk of a war between Israel and Hezbollah has grown following the strike in the Golan Heights that killed 12 children in a Druze village on Saturday and the subsequent killing of the senior Hezbollah commander Fuad Shukr.
The attack on Iranian soil and the killing of its close ally will put pressure on Tehran to react against Israel, which has been hunting Hamas leaders since the Islamist group attacked Israel on Oct. 7, killing 1,200 people and taking over 250 hostage, according to Israeli tallies.
In response, Israel launched a relentless 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 humanitarian crisis.
The assassination could also encourage Iranโs proxies in the Middle East who support Hamas โ Lebanonโs Hezbollah, Yemenโs Houthis and armed groups in Iraq โ to seek revenge.
Supreme Leader Khamenei said โFollowing this bitter tragic event which has taken place within the borders of the Islamic Republic, it is our duty to take revenge.โ
Iranโs top security body is expected to meet to decide Iranโs strategy in reaction to the death of Haniyeh, a close ally of Tehran, said a source with knowledge of the meeting.
Iran will โdefend its territorial integrity, dignity, honor, and pride, and will make the terrorist occupiers regret their cowardly actโ of killing Haniyeh in Tehran, President Masoud Pezeshkian said on Wednesday.
Palestinian President Mahmoud Abbas, Hamasโ rival, condemned the killing of Haniyeh and Palestinian factions in the occupied West Bank called for a general strike and mass demonstrations.
The killing of Ismail Haniyeh was around 2 a.m. (2200 GMT) on Wednesday, Iranian media reported. He was staying at โa special residenceโ for war veterans in north Tehran.
โFurther investigations are underway that will be announced soon,โ it said.
NourNews, an outlet affiliated with Iranโs Supreme National Security Council, said Haniyehโs residence was hit by an airborne projectile. The assassination was โa dangerous gamble to undermine Tehranโs deterrenceโ, it said.
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.
Hamas said it would continue the path it was following in the Gaza war, saying: โWe are confident of victory.โ
With Reuters inputs