By Kanishka SinghWASHINGTON, March 12 (Reuters) - President Donald Trump said that he thinks new Iranian Supreme Leader Mojtaba Khamenei, whose father, the former supreme leader, was killed on the first day of the U.S. and Israel's war on Iran, is alive but "damaged."Khamenei has not been seen by Iranians since his selection on Sunday by a clerical assembly, and his first comments were read out by a television presenter on Thursday.