Gambiaj.com – New details have emerged on circumstances of the assassination of Hamas political chief Ismail Haniyeh in the Iranian capital of Tehran on Wednesday using an explosive device that had been covertly hidden weeks prior, a source familiar with the matter tells CNN.

The bomb was concealed in a guest house where Haniyeh was known to stay, about two months ago, and detonated remotely once he was inside his room there, according to the source, who was briefed on the operation.

The New York Times was the first to report the details of Haniyeh’s assassination.

The Iranian government and Hamas say Israel carried out the assassination. Israel has neither confirmed nor denied its involvement.

US officials were briefed on the operation by Israeli officials only after the assassination, the source said.

Iranian state media and Hamas previously indicated Haniyeh was killed via a rocket fired from outside the building.

But the fact that the bomb was smuggled inside the guest house, which was under the protection of Iran’s Islamic Revolutionary Guard Corps, indicates a startling breach of security for the IRGC.

Iran’s Supreme Leader Ayatollah Ali Khamenei said Wednesday: “You killed our dear guest in our house and now have paved the way for your harsh punishment.”

It’s unclear when Haniyeh arrived in Tehran, but Iranian state media first reported that he would be flying in to attend the inauguration of the country’s new president on Monday. He had a full schedule of public appearances and meetings before he was assassinated, according to Iranian state media press reports.

Haniyeh was first pictured on Tuesday, before the inauguration, meeting with Iranian Supreme Leader Ayatollah Ali Khamenei. Afterwards, Iranian state media published images of Haniyeh meeting with Iran’s new President Masoud Pezeshkian. Haniyeh was next spotted arriving at the inauguration ceremony at Iran’s Islamic Consultative Assembly building, where he sat in the front row.

Just before 7:00 p.m. local time (11:30 a.m. ET), Haniyeh made his final public appearance at an exhibit at Tehran’s Milad Tower. At 2 a.m. that night, according to state media outlet IRNA, he was killed, with what IRNA described as an “airborne guided projectile.”

CNN is asking the Iranian government for reaction to this new reporting.

Haniyeh’s death is, both strategically and symbolically, a dramatic blow to Hamas, eliminating its most public figure who headed up the group’s political operations while living overseas.

His killing also sparked concerns over stalled negotiations to reach a deal for the release of hostages and a ceasefire in Gaza, where Israeli attacks have killed 39,840 Palestinians and razed patches of land into rubble-filled wasteland. Haniyeh played a leading role, representing Hamas in months-long truce talks.