Russia strongly condemned on Wednesday the Israeli aggression on Iran which resulted in the martyrdom of the chief of Hamas' political bureau Ismail Haniyeh.

Earlier today, the IRGC announced the martyrdom of Haniyeh in a missile targeting his place of residence in Tehran.

The assassination occurred while the senior Hamas leader was visiting the Iranian capital, Tehran, to attend the inauguration ceremony of the newly elected President Masoud Pezeshkian.

Read more: Global condemnations for assassination of martyr Ismail Haniyeh

"We strongly condemn this attack, which led to the death of Mr. Haniyeh," Kremlin spokesman Dmitry Peskov stated, adding that the Israeli strike on Iran was aimed at disrupting efforts to restore peace in the region and could significantly destabilize an already tense situation.

Deputy Foreign Minister Mikhail Bogdanov described the Israeli assassination of martyr Haniyeh as an "completely unacceptable political assassination" that will fuel regional tensions.

"This is all very bad. This is an absolutely unacceptable political murder, and it will lead to further escalation of tensions," he told RIA Novosti.

The IRGC vowed that the Resistance Axis will make "Israel" pay a heavy price for its "criminal and cowardly" assassination of Hamas' Politburo chief.

Read more: Israeli shekel loses 1.2% of its value following Haniyeh's martyrdom

"The heinous crime committed by the Zionist regime in killing Ismail Haniyeh... will undoubtedly be met with a harsh and painful response from the powerful Resistance Front," the guards corps said in a statement.

Iranian leader Sayyed Ali Khamenei stressed that retribution for Haniyeh's blood is "Iran's duty because he was martyred on our soil," adding that the Israeli entity "brought upon itself the most severe punishment."

Pezeshkian mourned the head of the Political Bureau of Hamas, saying, "Iran mourns its partner in sorrow and joy, the longtime and proud companion on the path of resistance."

"Yesterday, I raised the victorious hand of Hajj Ismail Haniyeh, the martyr of Al-Quds, and today I must [carry him] on my shoulder to bury him," he said.

The Iranian president pledged that the Islamic Republic will fiercely defend its honor and territorial integrity, ensuring that terrorist invaders deeply regret their cowardly actions.

The Islamic Republic of Iran announced a three-day mourning period.