Colombian troops killed nine FARC dissidents in a raid Friday in what the president said was “a clear message” to their leaders who have formally rejected a 2016 peace agreement and announced a return to arms. President Ivan Duque said he had authorized the military operation in rural areas of Colombia’s south. On Thursday, Duque said he would send a special army unit “with reinforced intelligence, investigation and mobility capabilities” to hunt down dissident leader Ivan Marquez and other holdouts.