sentences:  The two countries share an 11-kilometer border, with the Aras River separating Turkey from the Nakhchivan exclave of Azerbaijan.A war between Azerbaijan and neighbouring Armenia broke out shortly after the parliament of Nagorno-Karabakh, an autonomous oblast in Azerbaijan, voted to unify the region with Armenia on February 20, 1988.The Armenian demand to unify Karabakh with Armenia, which proliferated in the late 1980s, began in a relatively peaceful manner; however, as the Soviet Union's disintegration neared, the dispute gradually grew into a violent conflict between the ethnic groups in Nagorno-Karabakh, resulting in ethnic cleansing by all sides.