Niki Sumi, the self-styled military advisor of NSCN-K, is said to be the brain behind the June 4 attack on an Army convoy in Manipur, government officials said.
Quoting intelligence inputs, the officials said Sumi, who hails from Nagaland, drew up the entire conspiracy from Myanmar along with two other commanders of NSCN-K and one KYKL militant leader.
Sumi was the commander of the NSCN-K camp in Ponue in Myanmar, which was attacked by the Army on June 9 from Nagaland side. But Sumi had left the camp by then.
It is believed that 15 NSCN-K insurgents at the camp were killed in the attack by the commandos of Indian Army's special forces, officials said.
Sumi is reportedly changing his location every fortnight to avoid detection by Indian intelligence agencies. He has been working under the direct supervision of NSCN-K supremo S S Khaplang who is also wanted for hatching the whole conspiracy.
The other two senior NSCN-K insurgents identified by the intelligence agencies for the June 4 attack conspiracy were Neymlang, the "Major General" of NSCN-K, and Starson Lamkang, the head of finance wing of the group, who is suspected to have facilitated the attack, officials said.
Following the killing of the 18 Army soldiers, commandos of Special Forces had carried out a strike in the militant camps deep inside Myanmar.
Government has also decided to ban NSCN-K again for its recent violent activities after abrogating the ceasefire agreement with the Centre.