My immediate visualization upon reading the thread title was of a guy in winter camo, wearing a blue helmet with his arms raised in the air surrendering... then I realized you said NATO and not UN.
The idea has been rolling around in my head for awhile , another idea I had was for a kinda spin on harold covingtons "the brigade" but instead something to do with world in conflict where a large scale invasion happens of the Western USA... with partisan efforts cutting the Soviet efforts in the back with the War crippling the Soviets by late 80s leading to the inevitable collapse of the Soviets with one last area of control in the Pacific North West being held with outter regions being held by warlords and other militants trying to carve out proto states and any type fiefdom or hermit kingdom they can out of the isolated region before the USA swoops in a finishes off the rest of the rabble..
The idea was a lone GRU colonel in-charge of Coin from Seattel along with other elements from the Syrian Republican Guard and Cuban Special Forces hold the surrounding area with a garrison of local troops the colonel (Named Promachek) makes a decision to take control of the region and unite the fighting warlords into a larger state disobeying orders against far off dying state and his inevitable return to nothing for his service... so he goes AWOL.. leading an overthrow of those loyal to the CCCP coalition force forming a new regime loyal to his cause of creating a new state called "the peoples free state of the Northwest" with a large scale Sino Soviet split underway many of the fighters who later create the new regimes Congressional decide to work with the Chinese , Iranians , Syrians (who later choose the Free State Government over the Soviets) Libya , Pakistan , Sudan , Nicaragua
They also seize an area called the British Columbian Autonomous area or BBC which was originally held by local warlords and ally with guerrillas who wish to join the republic leading to many of the French Canadian speaking locals starting a guerrilla war to reunify with Canada which would last decades with many more demanding full fledged Independence for a French speaking nation in the north west for there people among the more radical groups
There is later though a schism caused by most of the congress being made up of the more left wing "The Free State Union for labor" a block of Socialist , newer ANCOM (mostly being created by encourage western Intelligence coordination from the UK and the USA) and Progressive parties which have created larger division by notching up the System to avoid Politically conservative left wing or Right wing parties from being allowed seats in the Congressional leading to the a new faction being formed "The Salvation for a free Republic of the Northwest" which leads to secession of the Faction with attempts to reunify and possibly enlarge the state against the pro western puppets of the Free state union Faction backed by the west and the russian federation..
with the eastern countries backing the far right and far left factions in the Salvation of the Republic Faction , leading to a civil war with the Warlords now formed into a Quasi Political Coalition just to survive and many other now political rebel factions now forming