A senior Defense Department official, who was not authorized to speak publicly and who spoke on the condition of anonymity, said that there would no longer be any more recruiting of so-called moderate Syrian rebels to go through training programs in Jordan, Qatar, Saudi Arabia or the United Arab Emirates. Instead, a much smaller training center would be set up in Turkey, where a small group of “enablers” — mostly leaders of opposition groups — would be taught operational maneuvers like how to call in airstrikes.