MOSCOW (Reuters) - Former militants from  bandit units  in Syria are now a real threat after the defeat of Islamic State, as many of them may be now planning to return to Russia, the RIA news agency cited the head of Russia s FSB security service as saying on Tuesday. The FSB head, Alexander Bortnikov, also told a meeting of Russia s National Anti-Terrorism Committee the security service had uncovered an underground cell of extremists from Central Asia planning to carry out  terrorist acts  during the New Year and Russia s 2018 presidential campaign in the Moscow region. 