By Christian Edwards, CNN
(CNN) — The killing of Ayatollah Ali Khamenei by the United States and Israel has created a power vacuum in the core of the Iranian regime and sparked the complex process of finding his successor.
The Islamic Republic has only replaced its supreme leader once since it swept to power nearly half a century ago. Khamenei, who succeeded Ayatollah Ruhollah Khomeini in 1989, was killed without an officially declared heir.
A three-person council was formed Sunday to hold power until Khamenei’s successor is chosen. But with the US-Israeli strikes ongoing, there is no indication of how long that might take.
Here’s what to know.
Who’s in charge right now?
Under Iran’s constitution, a three-person leadership council holds power until the new supreme leader is named. It includes the moderate president, Masoud Pezeshkian, the hard-line head of the judiciary, Gholamhossein Mohseni Ejei, and a senior cleric, Alireza Arafi.
The powerful speaker of Iran’s parliament, Mohammad Bagher Ghalibaf, said the regime had “prepared ourselves for these moments” and “planned for all scenarios.”
“With the formation of a leadership council, an unimaginable power and cohesion will take shape,” he said.
What it may not have planned for, however, is to have lost several of its most senior officials at once. Israel has claimed that a “majority” of Iran’s senior military leaders were killed in Saturday’s strikes, including the armed forces chief of staff, Maj. Gen. Abdolrahim Mousavi; the commander of the Islamic Revolutionary Guard Corps, Maj. Gen. Mohammad Pakpour; and the secretary of Iran’s Defense Council, Ali Shamkhani.
When Khomeini died in 1989 — after the Iran-Iraq War, which lasted most of that decade — it took less than a day for Khamenei to be named as his successor, meaning there was no need to form a transition council. With US-Israeli strikes ongoing, naming Khamenei’s successor will take longer.
Until then, the temporary council must decide whether to continue delegating defense decision-making to Ali Larijani, Iran’s top national security official, and Ghalibaf. Both men were tasked with leading Iran’s defense during the 12-day war with Israel in June, along with Shamkhani, a former navy rear admiral who was killed in Saturday’s strikes.
Who chooses the new leader?
A body of 88 senior clerics, known as the Assembly of Experts, will select Khamenei’s successor.
The members of the Assembly of Experts, which is elected by the Iranian public every eight years, are vetted by the Guardian Council, a separate body of 12 jurists that oversees the activities of Iran’s parliament.
In normal times, the Guardian Council determines if legislation passed by the parliament is compatible with sharia law, and it often demands revisions. It also approves candidates for parliament, the presidency and the Assembly of Experts.
It is known for disqualifying candidates for the presidency. Ahead of the 2021 election, for instance, the Guardian Council barred over 600 applicants, including all the women as well as senior figures such as Larijani, the top national security official.
Sanam Vakil, director of the Middle East and North Africa program at the Chatham House think tank, said the Assembly of Experts may not convene until the US and Israel wind down their operation. “They cannot risk further death and damage to the institution,” she told CNN.
Who are the contenders?
Khamenei’s second son, Mojtaba, is a significant figure with strong links to the Islamic Revolutionary Guard Corps (IRGC), the elite wing of Iran’s military, as well as the Basij, a volunte