Russian President Vladimir Putin denounced the assassination of Iran’s Supreme Leader on Sunday, labeling the killing, which occurred during a joint U.S.-Israeli strike, a “cynical violation” of established norms.

The Kremlin made Putin’s statement public in a letter addressed to Iranian President Masoud Pezeshkian following Khamenei’s death. The audacious daytime strikes on Saturday resulted in the deaths of Khamenei and multiple other senior Iranian officials, such as the commander of the Iranian Revolutionary Guard Corps.

“Please accept my profound condolences regarding the murder of the Supreme Leader of the Islamic Republic of Iran, Seyed Ali Khamenei, and his family members, an act carried out in cynical defiance of all principles of human morality and international law,” the letter stated.

“In Russia, Ayatollah Khamenei will be recalled as a distinguished statesman who played a major personal role in fostering friendly Russian-Iranian ties and elevating them to a comprehensive strategic partnership,” Putin added.

“I request that you convey my most heartfelt sympathies and support to the Supreme Leader’s family and friends, the government, and all the people of Iran,” he concluded.

At a U.N. Security Council meeting, Iranian Ambassador to the United Nations Amir-Saeid Iravani criticized the coordinated U.S.-Israeli attacks that targeted his nation all day Saturday.

Iravani charged the U.S. with contradicting its professed goals of international stability by assaulting a sovereign nation over its internal affairs.

“Neither the U.N. charter nor international law accept a state’s domestic matters as a valid reason for other states to use force. This would substitute the rule of law with the rule of force,” Iravani stated.

“Iran will persist in decisively exercising its right to self-defense without hesitation until the aggression stops completely and unconditionally.”

On Saturday morning, the U.S. ordered the commencement of Operation Epic Fury, pointing to Tehran’s persistent nuclear weapons development efforts.

“It has always been the policy of the United States, especially under my administration, that this terrorist regime can never possess a nuclear weapon. I’ll repeat it. They can never have a nuclear weapon,” Trump remarked on Saturday regarding the assault.

Trump stated that the strikes were intended to “defend the American people by removing imminent threats from the Iranian regime” and were launched after Iran declined to halt its nuclear development plans.

Iravani described the assault as an extension of the United States’ prolonged aggressive stance towards Iran.

“Mr. president, this morning the United States regime, in a joint and coordinated action with the Israeli regime, began an unprovoked and premeditated aggression against Iran for the second time in recent months,” Iravani said, alluding to U.S. strikes on Iranian nuclear sites the previous year. “The U.S. president and the Israeli prime minister have publicly admitted responsibility for this aggressive act and have clearly stated regime change as their goal, an unambiguous confession of their aim to breach Iran’s sovereignty and territorial integrity.”

‘ Leo Briceno and Reuters contributed to this report.