Lachin corridor in the context of "Peacekeeping operations in Nagorno-Karabakh"

Artsakh (/ˈɑːrtsɑːx, -sæx/ ART-sa(h)kh), officially the Republic of Artsakh or the Republic of Nagorno-Karabakh (/nəˌɡɔːrnoʊ kərəˈbɑːk/ nə-GOR-noh kər-ə-BAHK), was a breakaway state in the South Caucasus whose territory was internationally recognised as part of Azerbaijan. Between 1991 and 2023, Artsakh controlled parts of the former Nagorno-Karabakh Autonomous Oblast of the Azerbaijani Soviet Socialist Republic, including its capital Stepanakert. It had been an enclave within Azerbaijan from the 2020 Nagorno-Karabakh war until the 2023 Azerbaijani offensive, when the Azerbaijani military took control over the remaining territory controlled by Artsakh. Its only overland access route to Armenia after the 2020 war was via the five-kilometre-wide (3.1 mi) Lachin corridor, which was placed under the supervision of Russian peacekeeping forces.

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. A brief war over the region broke out in 1920. The dispute was largely shelved after the Soviet Union established control over the area, and created the Nagorno-Karabakh Autonomous Oblast (NKAO) within the Azerbaijan SSR in 1923; however, throughout the Soviet period, Armenians in the Nagorno-Karabakh Autonomous Oblast were heavily discriminated against. The Soviet Azerbaijani authorities worked to suppress Armenian culture and identity in Nagorno-Karabakh, pressured Armenians to leave the region and encouraged Azerbaijanis to settle within it, although Armenians remained the majority population.

The blockade of Nagorno-Karabakh was an event in the Nagorno-Karabakh conflict. The region was disputed between Azerbaijan and the breakaway Republic of Artsakh, internationally recognised as part of Azerbaijan, which had an ethnic Armenian population and was supported by neighbouring Armenia, until the dissolution of the Republic of Artsakh on 28 September 2023.

On 12 December 2022, under the guise of environmental protests, the Azerbaijani government launched a blockade of the Republic of Artsakh by sending citizens claiming to be eco-activists to block the Lachin corridor, a humanitarian corridor which connected Artsakh to Armenia and the outside world. Disguised military personnel, civil servants, members of pro-government NGOs, and youth organisations were among the so-called activists. The Azerbaijani government consolidated its blockade by seizing territory around the Lachin corridor both within Artsakh and Armenia, blocking alternative bypass routes, and installing military checkpoints. Azerbaijan also sabotaged critical civilian infrastructure of Artsakh, crippling access to gas, electricity, and internet access.

The political status of Nagorno-Karabakh remained unresolved from its declaration of independence on 10 December 1991 to its September 2023 collapse. During Soviet times, it had been an ethnic Armenian autonomous oblast of the Azerbaijan Soviet Socialist Republic. Following the dissolution of the Soviet Union, a conflict arose between local Armenians who sought to have Nagorno-Karabakh join Armenia and local Azerbaijanis who opposed this.

The conflict soon escalated into ethnic cleansing and open warfare in the First Nagorno-Karabakh War, as a result of which the region came under the control of an Armenia-allied de facto state, the Republic of Artsakh. The surrounding regions of Azerbaijan were occupied by the self-declared republic under the justification of a "security belt," which was intended to be exchanged for recognition of autonomous status from Azerbaijan.