Mojtaba Khamenei formally became the new Supreme Leader of Iran on March 8. The 56-year-old is the slain former leader Ayatollah Ali Khamenei's son. Mojtaba is now the third Shiite leader since the 1979 Islamic Revolution. The decision was taken by the 88-member Assembly of Experts of Shiite clerics. Ayatollah Ali Khamenei was killed in the US-Israeli strikes on Iran when the war began. The US President Donald Trump Mojtaba will not last long, calling him a 'lightweight'. Israel's military previously threatened to target any successor.