Acting on a tip off, the Khonsa battalion of the Assam Rifles apprehended the cadre who is a self-styled major of the militant organisation.
A pistol along with ammunition, 30 gram of opium, some cash and documents were recovered from his possession, Kohima-based Defence spokesman Col Chiranjeet Konwer said.
During interrogation, the militant revealed that he had joined NSCN(K) in 1999 and defected to NSCN(R) in 2015 and again shifted his allegiance to NSCN(IM) last year.