President Trump presented on Sunday his case for going to war with Iran and toppling the current regime — and warned more U.S. soldiers will likely die before the operation ends.Why it matters: Trump is publicly bracing the country for a sustained, costly military campaign, a sign America has entered an open-ended war with a rising human cost.Trump touted the elimination of Iran's supreme leader, Ayatollah Ali Khamenei, and framed the war as the only way to prevent Iran from becoming a nuclear-a...