TEHRAN, Iran 

The assassination of Hamas political bureau leader Ismail Haniyeh was "designed and executed" by Israel with support from the US, using a short-range projectile, Iran’s Islamic Revolutionary Guard Corps (IRGC) said on Saturday.

In a statement, the IRGC called the assassination a “terrorist crime” and vowed “severe punishment.”

Haniyeh was assassinated early Wednesday at his residence in the capital Tehran in a mysterious attack that Iranian officials blamed on their arch-foe Israel. Haniyeh’s bodyguard was also killed.

Haniyeh was in Tehran to attend the inauguration of Iran’s new president, Masoud Pezeshkian.

Haniyeh’s funeral was led by Iran’s Supreme leader Ayatollah Ali Khamenei on Thursday morning, followed by a massive procession. He was laid to rest on Friday in Doha, Qatar.

The IRGC said investigations found that the “terrorist operation” involved the firing of a short-range projectile with a warhead weighing some 7 kilograms (15.4 pounds), accompanied by a large explosion, from outside the place where Haniyeh was staying.

The statement added that the blood of Haniyeh “will be avenged” and Israel will receive a “decisive response at the appropriate time, place, and manner.”

Tensions are running high amid speculation that Iran is preparing a military response to Haniyeh's assassination that is bigger in scope than the operation that followed an attack on the Iranian Consulate in the Syrian capital Damascus in April.

In his reaction to the incident on Wednesday, Khamenei said Iran considers it a duty to “avenge the eminent guest’s blood,” vowing “severe punishment.”

Pezeshkian also condemned the assassination, pledging to “defend the country’s territorial integrity, honor and dignity.”