Turkey needs to do more in the fight against Islamic State militants and has indicated it is willing to go beyond its recent decision to allow US planes to conduct air strikes from Turkish bases, Defense Secretary Ash Carter said on Thursday. Carter said Turkey had agreed in principle to participate in the coalition bombing campaign against the militants, but the United States also needed Ankara to step up its efforts to control its long border with Iraq and Syria. “It’s a border over which logistics for ISIS and the fighters cross,” Carter said. “So we’re looking for them to do more in that regard as well and are in active discussions with them about that.” Turkey was expected to participate in air strikes against Islamic State in Syria after it reached a deal with the United States on greater participation in the campaign against the group. But Turkish bombing efforts have primarily focused on the Kurdish PKK, which it considers a terrorist group.