From Caucasus: An Introduction, by Thomas de Waal (Oxford U. Press, 2010), Kindle Loc. 2010-2032:
All the wars of the South Caucasus are case studies of the strange phenomenon whereby neighbors who have coexisted peacefully for years can end up fighting one another. Karabakh is a striking example. One village named Tug in the south of Karabakh had been home to people of both communities, with only a small stream dividing them. At first, the Armenians and Azerbaijanis of Tug said that the dispute would not affect them; then they retreated to their own half of the village, with some families being broken up; finally, in 1991, the Azerbaijanis were driven out by force.
The problem can be described as “mutual insecurity.” In tsarist times, pogroms had broken out when the regime weakened. In Soviet times, order was maintained by a central “policeman,” but when that law enforcer withdrew, the two national groups turned to their own armed men to protect them. Then in 1991 the Soviet armed forces collapsed into indiscipline, arming both sides and providing hundreds of “guns for hire.” This helped elevate a low-intensity conflict into an all-out war fought with tanks and artillery.
Another answer to the puzzle of neighbors fighting one another is that generally it was not they who actually started the conflict. Many Armenians and Azerbaijanis, like the people of Tug, did their best to resist the slide toward war. In the spring of 1991, the revolutionary California-born Armenian warrior Monte Melkonian was sent on a commission down Armenia’s border with Azerbaijan to prepare villages for impending conflict. He got frustrated as villagers asked him and other would-be defenders to leave, saying they did not want to fight their Azerbaijani neighbors.
Moreover, although ordinary Armenians and Azerbaijanis lived side by side, the views of their intellectual elites were sharply different. Each harbored memories of the wars of the tsarist era and subscribed to nationalist ideas, which had been boosted by the officially tolerated nationalism of the late Soviet period. In 1988, some intellectuals often played a negative role by disseminating narratives of hate. The Armenian writer Zori Balayan wrote that the Azerbaijanis were “Turks” who had no history of their own. The Azerbaijani historian Ziya Buniatov wrote an inflammatory pamphlet suggesting that the Armenians themselves had been behind the killing of Armenians in Sumgait.
After the intellectuals came the men of violence. As the Soviet security apparatus withered, the initiative was handed to people who have been called “entrepreneurs of violence.” They were people who were often marginal figures in society but willing or able to fight. Violence became self-fueling. In the later war in Abkhazia, much of the most brutal fighting would be done by people from outside Abkhazia itself—North Caucasians on the Abkhaz side, incoming Georgian paramilitaries on the Georgian side. These guns-for-hire would exact a tithe for their fighting in looting and plunder.