US Secret Service Director Kimberly Cheatle resigned after the agency came under harsh scrutiny for its failure to stop a would-be assassin from wounding former President Donald Trump during a campaign rally, the White House said on Tuesday. The Secret Service, which is responsible for the protection of current and former US presidents, faces a crisis after a gunman was able to fire on Trump from a roof overlooking the outdoor rally in Butler, Pennsylvania, on 13 July. “The independent review to get to the bottom of what happened on 13 July continues, and I look forward to assessing its conclu…