US freezes funding contributions to Haiti multinational security force: UN / US freezes funding for multinational force tackling Haiti gangs / El Salvador joins U.N.-backed mission on the ground in Haiti to combat gang violence / UN chief warns gangs could overrun Haiti's capital without additional international security support / Haiti's new prime minister promises security to a country reeling from recent massacres / US to evacuate some diplomats from Haiti after recent gang attacks: Reports / Haiti's interim leader seeks 'urgent' overseas help to shore up security / UN extends Haiti security mission for another year as violence soars / US-backed mission in Haiti struggles to take on gang violence