Iran has launched an extensive investigation into the killing of Ismail Haniyeh, the head of the political office of Hamas, and arrested dozens possibly connected, a New York Times report said Saturday.

Citing two sources familiar with the investigation, the NYT report said senior intelligence officers, military officials, and staff workers at a military-run guesthouse in Tehran where Haniyeh was assassinated, were detained.

Iran’s Islamic Revolutionary Guards Corps (IRGC) specialized intelligence unit has taken over the investigation, according to the NYT’s sources.

The assassination dealt a critical blow to Iran’s security apparatus, exposing severe vulnerabilities and indicating deep foreign intelligence penetration within the Islamic Republic, analysts told Al Arabiya English on Thursday, shortly after the shock attack.

The experts added that the assassination was a message to Iran and its allies and proxy groups; they are not beyond Israel’s reach, even in Tehran.

Although Israel has not claimed responsibility for the killing of Haniyeh, and US officials told Al Arabiya English that they were not involved, Israeli forces are thought to be behind the killing.  

Some reports, including from Hamas and Iranian media, state that Haniyeh was killed by a missile strike. Other reports suggest that a bomb smuggled into the secure facility caused his death.

Haniyeh has led the Palestinian group, designated a terrorist organization by the US, from Qatar. He was in Tehran to attend the inauguration of Iran’s new president.

What happened after the killing

The NYT reported that after the attack, Iranian officials raided the guesthouse compound, which belongs to the IRGC, placed staff members under quarantine, arrested some, and confiscated all electronic devices, including personal phones.

Haniyeh reportedly frequented the guesthouse, and often used the same room, during his visits to Tehran.

At the guesthouse, CCTV footage was scanned thoroughly, guest lists were checked, and examined the day-to-day of personnel, the NYT report said, adding that they are operating under the belief that members of the Israeli Mossad who were involved in the assassination are still in the country.

Another batch of investigators are reportedly scouring footage from Iran’s international and domestic airports, scanning arrival and departure lists and CCTV footage.

A member of the IRGC told the NYT that security protocols have changed, security personnel guarding senior officials have been swapped, and electronic equipment like phones have also been replaced.

Rising tensions

Many in the region, including Iran, Yemen’s Houthis, and Hamas have vowed revenge against Israel for the killing, resulting in a tense situation for the region.

Tensions are already high in the Middle East following an initial escalation between Israel and the Palestinian Hamas militant group late in 2023, and then the subsequent involvement of other Iran-backed proxy groups including Hezbollah and Yemen’s Houthis in support of Gazans who are being killed indiscriminately by the Israeli forces.

Late Friday, Al Arabiya English reported that US Defense Secretary Lloyd Austin ordered the deployment of additional fighter jets along with ballistic missile defense-capable cruisers and destroyers to Europe and the Middle East in response to the recent threats.

The Pentagon is also taking steps to prepare to deploy additional land-based BMD systems.

There are around 30,000 US troops in the Middle East, with Qatar’s Al-Udeid, as the largest military base. The Pentagon ordered several warships and other military assets to the Middle East shortly after the Oct. 7 Hamas attack on Israel, mainly as deterrence to Iran and its proxy groups from opening a second front.