For decades, power in Iran was centralized in the hands of a single man: Supreme Leader Ayatollah Ali Khamenei. But since his killing at the onset of the US-Israeli war with Iran on February 28, decision-making in Tehran has become increasingly decentralized, experts say. Mojtaba Khamenei has not been seen in public since he succeeded his father in early March. In his absence, a cohort of senior Iranian officials have been effectively running the country. The Islamic Revolutionary Guards Corps (IRGC), a dominant political player, has now become…