In 1991, a referendum held in the NKAO and the neighbouring Shahumian region resulted in a declaration of independence based on its right of self-determination.
Large-scale ethnic conflict led to the 1991–1994 Nagorno-Karabakh War, which ended with a ceasefire that left the current borders.
The EU announced it was "aware that a 'constitutional referendum' has taken place," but emphasised its stance that only a negotiated settlement between Azerbaijan and ethnic Armenians could bring a lasting solution.
Artsakh controls most of the territory of the former Nagorno-Karabakh Autonomous Oblast and some of the surrounding area, giving it a border with Armenia to the west, Iran to the south, and the uncontested territory of Azerbaijan to the north and east.
The predominantly Armenian-populated region of Nagorno-Karabakh was claimed by both the Azerbaijan Democratic Republic and the First Republic of Armenia when both countries became independent in 1918 after the fall of the Russian Empire, and a brief war over Nagorno-Karabakh broke out in 1920.
The Prime Minister's post was abolished and the executive power is now residing with the President who is both the head of state and head of government.
The president is directly elected for a maximum of two-consecutive five-year terms.
Another referendum was held on 20 February 2017, with a 87.6% vote in favour on a 76% turnout for instituting a new constitution.
This constitution among other changes turned the government from a semi-presidential to a fully presidential model, and changed the official name from the "Republic of Nagorno-Karabakh" to the "Republic of Artsakh"/"Artsakh Republic".) between 19, is an unrecognised republic in the South Caucasus.The region is considered by the UN to be part of Azerbaijan, but is under the control of ethnic Armenian separatists.The First article of the document described the then Nagorno-Karabakh Republic as "a sovereign, democratic legal and social state".More than 100 non-governmental international observers and journalists who monitored the poll evaluated it positively, stating that it was held to a high international standard.In his 2015 speech, the President of Armenia Serzh Sargsyan stated that he considered Nagorno-Karabakh "an inseparable part of Armenia".