The killing of Hamas’s top political brass, Ismail Haniyeh, was planned months ago.

Newly released details of the assassination reveal that the bomb that killed the Hamas veteran was planted approximately two months ago and was so precise that other terror leaders staying in the same guesthouse were left unharmed.

According to seven anonymous Middle Eastern officials who briefed the New York Times, including two Iranians and an American official, the Hamas leader was killed by a device smuggled into the guesthouse where he was staying in Tehran.

The bomb, which was planted in a room that Haniyeh was known to have stayed in before, is said to have been detonated remotely once it was confirmed that the Hamas leader was inside the room after attending the inauguration of Iran’s new president, Masoud Pezeshkian, according to five officials.

When it was detonated at around 2 am, the explosion shook the guesthouse, shattered some windows and destroyed part of an exterior wall, according to several IRGC officials. Photos from the area suggest the blast had minimal impact beyond the building, which makes it unlikely the explosion came from a missile, as was previously speculated.

According to the New York Times, guesthouse staff ran towards the centre of the noise and found Haniyeh and his bodyguard. Medics rushed to the scene and declared that Haniyeh had been killed by the immediate impact of the blast. The medical team tried to revive Haniyeh’s bodyguard, but he too was declared dead at the scene.

The leader of the Palestinian Islamic Jihad, Ziyad al-Nakhalah, was staying next door to Haniyeh but his room was barely damaged and he was unharmed, according to two Iranian officials, indicating the precise, planned targeting of Haniyeh.

Shortly after the explosion, news spread about the possibility that Haniyeh was killed by an Israeli missile fired from a drone or a plane, similar to the one launched on an Iranian military base in April, or that which killed Hezbollah’s senior commander Fuad Shukr in Beirut on Wednesday.

But the targeted tactics of the precision attack were more similar to the remote AI robot weapon that Israeli forces used to kill Iran’s chief nuclear scientist Mohsen Fakhrizadeh from inside Israel about a thousand miles away in 2020. The weapon that killed Haniyeh could have also been detonated from outside Iran.

Haniyeh was known to have stayed at the guesthouse in an upscale neighbourhood of northern Tehran several times. Part of a compound, known as Neshat, the guesthouse is run by the Islamic Revolutionary Guards Corps and is used for retreats, secret meetings, and housing prominent guests.

Three Iranian officials told the New York Times that the breech in Iran’s defenses in the compound which was supposedly tightly guarded by the IRGC was a “catastrophic failure of intelligence” and an embarrassment for the IRGC.

It remains unclear how the bomb was hidden in Haniyeh’s room, but officials suggest that it took months to plan and the guesthouse would have been extensively surveilled by Israeli intelligence.

Israel is yet to publicly acknowledge carrying out the attack, but Israeli officials are said to have briefed the US and other Western governments.

Iran has blamed Israel for the attack and US officials have also reportedly reached the same conclusion.

Operations outside Israel are carried out by the country’s foreign intelligence service, Mossad, who said after October 7 that they would track down the leaders of Hamas.