Iran’s Islamic Revolutionary Guard Corps (IRGC) has mourned the death of Supreme Leader Ayatollah Ali Khamenei, vowing swift retaliation and announcing what it described as a major forthcoming military operation.

In a statement carried by the semi-official Fars news agency, the IRGC said, “We have lost a great leader and we mourn him,” describing Khamenei’s death as martyrdom “at the hands of the most vicious terrorists and executioners of humanity.”

The statement said his killing was “a sign of the legitimacy of this great leader and the acceptance of his sincere services,” and warned that the “Iranian nation’s hand of revenge…will not let them go.”

The IRGC pledged to stand “firm in confronting domestic and foreign conspiracies,” signalling that Tehran would not retreat in the face of escalating conflict.

In a subsequent statement published by Fars, the Guard Corps announced the launch of what it called “the most devastating offensive operation in the history of the Islamic Republic of Iran.”

The offensive, it said, would begin “in just moments” and would target what it described as the “occupied territories and American terrorist bases” in the region.

There was no immediate response from Israel or the United States to the announcement.