[6][7] After more than a decade of unfruitful talks with the Indian authorities, including Prime Minister Jawaharlal Nehru, Zapu Phizo, the NNC chairman, lost faith in the diplomatic process.

Over 130 military personnel were trained and indoctrinated in Tengchong, Yunnan, and returned to Nagaland with brand-new Chinese equipment, including rifles and rocket launchers.

Colonel Taka left Nagaland in January 1968, but they were blocked by Kachin Independence Army (KIA) members, and turned back after having their weapons confiscated.

However, those inspecting the implementation of the accord observed that weapons that had been surrendered were old and outdated and inferred that the best weaponry of the underground forces had been sent across the border to units entrenched in Burma's frontier region.

[15] The Shillong Accord brought relief both to the battle-weary insurgent military personnel, as well as to the civilians living in areas where Indian authorities had put counter-insurgency measures in place.

[16] The cessation of hostilities in 1975, meant that the Naga Army personnel fighting inside Nagaland had accepted defeat, conceding the operational victory to the Indian military.

Muivah, along with Isak Chishi Swu, wanted to keep the armed struggle going against India and denounced the signatories of the accord in the most severe terms: "In spite of 'the bitterest pressure they have been subjected to, the Nagas will forever hold their own … any talks, any negotiations tending to [include Nagaland] within the Indian Union are unequivocally the works of hidden traitors who in no way represent the people'.

[16][18] The tensions generated in the wake of the acceptance of the Shillong Accord by the NNC culminated in the establishment of the NSCN (National Socialist Council of Nagaland) on 31 January 1980.

[18] From their sanctuary in a remote area of Burma where the last remnants of the Naga Army had taken refuge, Isak Chisi Swu, Thuingaleng Muivah and S.S. Khaplang, had begun in November 1979 by killing all the top leaders who opposed their new guidelines.

These included Naga army officers of different ranks, as well as important political figures, such as the NNC vice President, the Speaker of the Tatar Hoho, and some ministers.

[16] In this ruthless manner the more radical NSCN co-opted the remaining fighting units of the Naga nationalist movement and deprived the more moderate NNC of a military branch.

From the onset, the insurgency led by the NSCN mirrored the irregular warfare of numerous Marxist-Leninist revolutionary outfits present in the region of Northeast India, as well as in northern Burma.

Later, a number of other insurgent outfits of the area would be added to the grand plan, the NSCN helping them to procure weapons, providing training for their cadres, and extorting money in order to finance the operations of the group.

Besides the extorsion racket, the political wing used money earned through drug trade in order to pay for the training of the Naga Army cadres and procure arms.

The cargoes arrived by vessel to Cox's Bazar in Bangladesh, and were carried overland via Bandarban along the eastern border of Mizoram and through Churachandpur and Tamenglong they reached the Peren district of Nagaland.

It was during this period that the DGFI helped the NSCN (IM) —as well as the ULFA and the NDFB— to set up military training camps in the Chittagong Hill Tracts; additionally it provided safe houses in Dhaka and other locations in Bangladesh.

The Naga army cadres marched through safe routes across the mountainous terrain of the Garo Hills to bring the HALC recruits to the training facilities in Bangladesh.

[20] The Indian military along with the Intelligence Bureau became aware of the regular weapon supplies coordinated by the NSCN (IM) that were carried overland to Nagaland from Cox's Bazar.

In April 1995, after having monitored a sufficient amount of movements along the frontier region, they decided to act in a surprise attack named Operation Golden Bird.

The negotiations began in the summer and a ceasefire agreement was signed, which included the suspension of hostilities for a period of three months with effect from the 1 August 1997 in order to engage in political level discussions.

Although the cease-fire was meant for Nagaland, unofficially it was allowed to be extended to the Naga districts of Manipur, a provision that would eventually prove to be a crucial mistake on the part of the Indian Government.

However, the NSCN (IM) was not ready to give up its lucrative extortion business, hence though it didn't engage in killings for failure to pay, it cleverly used proxies in Manipur to continue demanding money.

In one instance, on 3 March 1999, an Assam Rifles post received information during the night that five groups totaling over hundred Naga cadres were crossing the border from Bangladesh and headed north.

The Assam Rifles set up an ambush and managed to catch the third group while taking a rest, killing six of the NSCN (IM) personnel and a collaborator, as well as wounding one.

A few days later the Assam Rifles Brigadier was met by senior NSCN (IM) party members of the Dimapur headquarters who objected to the attack on their cadres during the ceasefire and asked for the return of the weapons that had been seized.

[31] Again, on 16 March 2002, a NSCN (IM) vehicle carrying Naga military personnel from Chandel to Ukhrul, was stopped at a security checkpoint near Pallel manned by the Manipur Rifles.

Later there was a strong protest from the NSCN (IM) party leadership, but the government reminded them that, as part of the ceasefire agreement, the Naga cadres should not have moved with their weapons showing, and at any rate they should have stopped when challenged by the guards manning the checkpoint.