The Islamic Republic has begun six days of funeral ceremonies for Supreme Leader Ayatollah Ali Khamenei, more than four months after he was killed in a US-Israeli strike.

Stretching from Tehran and Qom to the Shiite holy cities of Najaf and Karbala in neighboring Iraq before concluding in Mashhad, the ceremonies are expected to become one of the largest state-organized events in the Islamic Republic's history. Authorities anticipate up to 20 million participants, have deployed more than 150,000 police officers, closed parts of the country's airspace and declared public holidays to facilitate attendance.

Yet beyond the immense logistical operation lies a far more consequential objective. For Tehran, Khamenei's funeral is not simply a religious ceremony but a choreographed political transition intended to demonstrate that the Islamic Republic remains unified, resilient and fully in control after losing the man who dominated its political system for more than three decades.

The ceremonies will also provide the first major opportunity for Iran's new leadership to project authority at home and abroad following the succession of Khamenei's son, Ayatollah Mojtaba Khamenei, at a time when the country is emerging from its most dangerous military confrontation since the Iran-Iraq War of the 1980s.