National Socialist Council of Nagaland-Khaplang (NSCN-K), a group which is allegedly responsible for killing of 18 army personnel in Manipur, has been declared a terrorist organisation under the stringent anti-terror law. In a gazette notification issued recently, the government declared NSCN-K, all its front organizations and formations as a terrorist organization under the Unlawful Activities (Prevention) Act, 1967, a Home Ministry spokesman said.