The First Nagorno-Karabakh War was an ethnic and territorial conflict that took place from February 1988 to May 1994 in the enclave of Nagorno-Karabakh in southwestern Azerbaijan between the majority ethnic Armenians of Nagorno-Karabakh backed by Armenia, and the Republic of Azerbaijan with support from Turkey. As the war progressed, Armenia and Azerbaijan, both former Soviet republics, entangled themselves in protracted, undeclared mountain warfare in the mountainous heights of Karabakh as Azerbaijan attempted to curb the Karabakh Movement.
The enclave's parliament had voted in favor of uniting with Armenia and a referendum, boycotted by the Azerbaijani population of Nagorno-Karabakh, was held, in which a 99.89% voted in favor of independence with an 82.2% turnout. The demand to unify with Armenia began in a relatively peaceful manner in 1988; in the following months, as the Soviet Union disintegrated, it gradually grew into an increasingly violent conflict between Armenians and Azerbaijanis, resulting in ethnic cleansing, including the Sumgait (1988) and Baku (1990) pogroms directed against Armenians, and the Gugark pogrom (1988) and Khojaly Massacre (1992) directed against Azerbaijanis.Inter-ethnic clashes between the two broke out shortly after the parliament of the Nagorno-Karabakh Autonomous Oblast (NKAO) in Azerbaijan voted to unite the region with Armenia on 20 February 1988. The declaration of secession from Azerbaijan was the culmination of a territorial conflict. As Azerbaijan declared its independence from the Soviet Union and removed the powers held by the enclave's government, the Armenian majority voted to secede from Azerbaijan and in the process proclaimed the unrecognized Republic of Nagorno-Karabakh.