What to know about the Iran war:President Trump on Friday slammed NATO allies as "cowards" for not sending troops to help open the Strait of Hormuz, a critical waterway for the global oil trade that remains effectively closed amid Iran's continued retaliation for Israel's attack on the South Pars natural gas field.Thousands more U.S. Marines and three more warships are headed toward the Middle East, two U.S. officials told CBS News, as the war nears the three-week mark with no signs of letting up. This is the second Marine expeditionary unit the Pentagon has sent toward the region since the start of the conflict. Gas and oil prices remained well above pre-war levels Friday, with international standard Brent crude trading around $107, up more than 47% since the conflict began on Feb. 28.Mr. Trump and Israeli Prime Minister Benjamin Netanyahu have said ensuring Iran cannot build a nuclear weapon is one of their goals, but the head of the U.N.…