Iran’s foreign ministry has stated that it believes retaliating against Israel for the assassination of Hamas leader Ismail Haniyeh is “necessary.”

Nasser Kanaani, a spokesperson for the foreign ministry, said that while Iran does not seek to escalate tensions, it considers punishment a “necessary” response to Haniyeh’s killing in Tehran and to prevent further instability, according to Reuters and The Guardian.

No one has claimed responsibility for the attack on Haniyeh, but Iran and Hamas have both been accused of carrying out the strike.

This follows Iran’s rejection of calls by the U.S. and Arab countries to moderate its response to Haniyeh’s death. The U.S. warned that any significant strike would elicit a response and that new Iranian President Masoud Pezeshkian’s efforts to improve engagement with the West would be better received if Iran shows restraint, reported .

The U.S. also stated it was urging Israel to de-escalate tensions.

Iranian leaders informed Arab diplomats on Saturday that they do not care if their retaliation leads to war.

Israel has declared that it is prepared to defend against and respond to any retaliatory strike.

“Israel is now in a multifront war against the Iranian axis of evil,” Israeli Prime Minister Benjamin Netanyahu said on Sunday. “We are ready for any scenario, either defensive or offensive. I repeat to our enemies: We will respond and exact a heavy price for any act of aggression against us, from any arena.”

Haniyeh, who was in Tehran for the inauguration of Iran’s new president, was killed by a bomb while staying in an Islamic Revolutionary Guard Corps guesthouse, according to The Wall Street Journal, although Iran and Hamas have disputed this claim, instead stating that he was struck by a missile.

Israel has not publicly commented on the killing.

Reuters contributed to this report.