The Karabakh conflict, which has its roots in the great power struggles of the early 18th century, has escalated whenever the imperial control of the surrounding great powers – including Safavid Persia, the Russian Empire, and the Soviet Union – waned. In 1921, after the Red Army had conquered the entire South Caucasus, the Moscow controlled Caucasus Bureau of the Communist Party declared Armenian-populated Nagorno-Karabakh an autonomous region. However, this region was administratively part of the newly created Soviet Republic of Azerbaijan, which led to frequent tensions between Karabakh Armenians and Baku. The current phase of the conflict began during the perestroika era in
1987, when Karabakh Armenians attempted to join Soviet Armenia, prompting a violent response from Azerbaijan. Full-scale war broke out after the dissolution of the Soviet Union. Tens of thousands died on both sides, and hundreds of thousands were displaced. When a cease-fire was reached in 1994, the Karabakh Armenians emerged victorious, controlling territories well beyond the original borders of the Soviet Autonomous Region of Nagorno-Karabakh.

The search for a resolution to the conflict within the OSCE Minsk Group, co-chaired by the United States, Russia, and France, began almost simultaneously with the outbreak of the war in 1992. By the mid-2000s the sides had agreed on basic principles of conflict resolution, including ones for the non-use of force, Karabakh’s self-determination through a future referendum, and Azerbaijan’s territorial integrity. The latter included the return to Azerbaijan of territories captured by Armenian forces outside of Nagorno-Karabakh during the war, with the provision of a land corridor linking Armenia to Nagorno-Karabakh, the return of displaced persons, and the deployment of an international peacekeeping force. 

None of these proposals has ever been implemented. For more than two decades, an asymmetrical military balance maintained relative peace. While Azerbaijan was the larger power overall, the Armenians benefited from a strategic geographic advantage, holding the higher ground. However, this balance was increasingly disrupted in Azerbaijan’s favor. One factor was the support Azerbaijan received from Turkey. Under their “one nation, two countries” formula, Turkey and Azerbaijan signed a comprehensive military agreement in August 2010 and have since held regular joint military exercises. An increasing number of Azerbaijan’s military officers are trained in Turkey – reaching approximately 85 percent by 2020. Ankara has also played a significant role for Azerbaijan in operational planning and military intelligence, and Turkey emerged as a key supplier of arms to Azerbaijan. In particular, the latter includes the supply of “Bayraktar” drones,which diminished Armenia’s strategic geographic advantage. Other major arms suppliers to the Azerbaijani military include Israel, Russia, and the United States.

https://css.ethz.ch/en/center/CSS-news/2023/12/geopolitical-echoes-of-the-karabakh-conflict.html