US President Donald Trump considers the death of Iran's Supreme Leader, Mojtaba Khamenei, to be a 'rumor,' although he told NBC that 'no one' has been able to prove he is alive, after he issued a written message to the country this week in which only his photo was shown. 'I don't even know if he's alive. So far, nobody has been able to prove it,' the president said during a 30-minute telephone interview on Saturday. Trump insisted that he had heard that Khamenei, the son of the late Ayatollah Khamenei, 'is not alive,' but then pointed out that 'if he is, he should do something very smart for his country, and that is to surrender.' However, the president called the news of his death a 'rumor.'