In 1988, the Armenians of Karabakh voted to secede and join Armenia. This was met by pogroms of Armenians chiefly in three cities of Azerbaijan: Sumgait, Baku, Kirovabad and led to the military conflict that became known as the Nagorno-Karabakh War. The war resulted in "de facto" Armenian occupation of former NKAO and seven surrounding Azerbaijani zones of similarly combined area and was effectively halted when both sides agreed to observe a cease-fire, which has been in effect since May 1994. In late 1995, both also agreed to the mediation of the OSCE Minsk Group. The Minsk Group is currently co-chaired by the US, France, and Russia and comprises Armenia, Azerbaijan, Turkey, and several Western European nations.