Threatening "violent armed conflict", the NSCN-IM on Friday sought a third-party intervention to address the impasse over the Naga political issue.
The group, which has maintained ceasefire since 1997, accused the Centre of "betraying" the Framework Agreement signed on August 3, 2015.
In a statement, NSCN-IM general secretary Th Muivah claimed the Centre was "deliberately refusing" to honor the key provisions of the historic agreement, specifically the recognition of the "Naga national flag and constitution"..
Muivah said NSCN-IM was committed to protect the unique history and "sovereignty" of Nagalim -- Naga-inhabited areas of Arunachal, Assam, Manipur and Nagaland, and parts of Myanmar -- and vowed that these principles were "non-negotiable" in any political settlement.
He said the Centre's failure to abide by the Framework Agreement could lead to a "renewed violent confrontation".
Muivah said the 2015 agreement, signed between the Centre and the NSCN-IM, was hailed for officially recognising the Naga issue as "a conflict between two sovereign entities".
It also acknowledged Nagalim's "sovereign national flag and constitution", marking a significant shift from the traditional stance that the conflict was an internal matter for India, he said.
Claiming that the Centre has betrayed the spirit of the agreement by refusing to formally recognise the Naga flag and constitution, Muivah said these was non-negotiable and should be part of any future political settlement.
The failure to honor these commitments would lead to the collapse of the peace process, he said.
He also called for a third-party intervention to mediate the impasse, suggesting that external mediation might be necessary.
He said that if the Centre rejected such a proposal, the NSCN-IM would have no choice but to resume "armed resistance in defense of Nagalim's sovereign existence".
"If India continues to ignore the terms of the Framework Agreement, the NSCN will be forced to take up arms again," Muivah said, maintaining that the NSCN-IM was prepared for any eventuality.
He, however, expressed hope for a peaceful resolution, stating that the Centre must recognise the Naga flag and constitution as part of the settlement.
Muivah said the peace process began in 1997 and over 600 rounds of talks have been held between the NSCN-IM and Centre since then.
Why Nagaland Is Baying For Army's Blood
After ULFA, 3 Naga groups unite for talks with Centre
'Minor confrontation' between Assam Rifles, NSCN-IM
NSCN-IM runs parallel govt in Nagaland: Delhi court
No going back on flag, Naga lands: NSCN-IM