Armenians and Azeris are engaged in a protracted conflict over the territory of Nagorno-Karabakh. It is a dispute dating back more than a century, but its most recent chapter began with the dissolution of the Soviet Union. Because most of Nagorno-Karabakh's population was ethnically Armenian, there was resentment that it had been incorporated into the Azerbaijan Soviet Socialist Republic, albeit as an autonomous region. And as the USSR started to crumble at the end of the 1980s, ethnic tensions flared into violence. Azeris fled Karabakh, known as Artsakh to ethnic Armenian residents; Armenians fled other parts of Azerbaijan. Full-scale war erupted between Armenian and Azerbaijani forces after Nagorno-Karabakh declared itself independent in late 1991 (a status still unrecognised internationally). More than 30,000 people were killed and one million displaced, before a 1994 ceasefire agreement left Armenian and Karabakh forces in de facto control of the region.
Despite years of peace negotiations – mediated by Russia, the United States and France as co-chairs of the OSCE Minsk Group – no final political solution has been achieved. Armenia continues to occupy Nagorno-Karabakh and seven areas around it, all internationally recognised as part of Azerbaijan, while Armenian and Azerbaijani forces face off along a 'line of contact' stretching for more than 100km. Fears of a new war have been growing since the start of 2009, with an increase of deadly ceasefire violations. Belligerent noises from Azerbaijan, and ramped-up military spending by both Baku and Yerevan, have added to those concerns. Tensions reached an all-time high in late August and early September of 2012 when a convicted murderer, who was serving time in Hungary for killing an Armenian military officer, was released in Azerbaijan. While there was a chance that the conflict could have escalated, it was largely contained to the diplomatic sphere and did not come to any serious armed clashes and the conflict remains frozen.