The Nagorno-Karabakh conflict is an ethnic and territorial conflict between Armenia and Azerbaijan over the region of Nagorno-Karabakh, inhabited mostly by ethnic Armenians until their expulsion in 2023, and seven surrounding districts, inhabited mostly by Azerbaijanis until their expulsion during the 1990s. The Nagorno-Karabakh region was entirely claimed by and partially controlled by the breakaway Republic of Artsakh, but was recognized internationally as part of Azerbaijan. Azerbaijan gradually re-established control over Nagorno-Karabakh region and the seven surrounding districts.
Throughout the Soviet period, Armenians in the Nagorno-Karabakh Autonomous Oblast were heavily discriminated against. The Soviet Azerbaijani authorities suppressed 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. Motivated by fears of cultural and physical erasure under government policies from Azerbaijan, the Karabakh Movement advocated for the reunification ("miatsum") of the enclave with Soviet Armenia. A referendum in 1988 was held to transfer the region to Soviet Armenia, citing self-determination laws in the Soviet constitution. The Karabakh Movement was met with a series of pogroms against Armenians across Azerbaijan, before violence committed against both Armenians and Azerbaijanis occurred.
The conflict escalated into a full-scale war in the early 1990s following the dissolution of the Soviet Union. The war was won by Artsakh and Armenia, and led to occupation of regions around Soviet-era Nagorno-Karabakh. Azerbaijan and Turkey responded with a transportation and economic blockade of Armenia which persists to this day, while Artsakh was also blockaded until 2023. There were expulsions of ethnic Armenians from Azerbaijan and ethnic Azerbaijanis from Armenia and the Armenian-controlled areas. The ceasefire ending the war, signed in 1994 in Bishkek, was followed by two decades of relative stability, which significantly deteriorated in the 2010s. A four-day escalation in April 2016 resulted in hundreds of casualties but only minor changes to the front line.
In late 2020, the large-scale Second Nagorno-Karabakh War resulted in thousands of casualties and a significant Azerbaijani victory. The hostilities subsided with a tripartite ceasefire agreement, under which Azerbaijan captured one-third of Nagorno-Karabakh and regained control over the occupied territories surrounding the region. Ceasefire violations in Nagorno-Karabakh and on the Armenian–Azerbaijani border continued following the 2020 war. Between 2022 and 2023, Azerbaijan escalated its blockade of Nagorno-Karabakh using a military checkpoint, sabotaging civilian infrastructure, and targeting agricultural workers. The ten-month-long military siege isolated the region from the outside world. In September 2023, Azerbaijan launched a large-scale military offensive, expelled the entire population, dissolved the government of Artsakh, and incorporated the territory into Azerbaijan. In August 2025, Azerbaijan and Armenia signed a US-brokered peace agreement in Washington, DC, aiming to end the conflict, reopen transport routes, and normalize relations. Barriers to a comprehensive and lasting settlement include Azerbaijan’s denial of the right of return for displaced Armenians, disputes over Armenians detained, and Azerbaijan's demands that Armenia concede an extraterritorial transit corridor and amend its constitution and national symbols.
Background
Following the breakup of the Russian Empire, the Armenians of Nagorno-Karabakh formed an unrecognised polity known as the Karabakh Council in 1918. Due to Azerbaijani–British pressure, the Karabakh Council in August 1919 was forced to provisionally recognise the authority of Azerbaijan, pending the Paris Peace Conference's adjudication of the international borders of the republics within the South Caucasus. As the peace conference was inconclusive regarding Nagorno-Karabakh, the Azerbaijani governor-general Khosrov bey Sultanov, issued an ultimatum to the Armenians of Karabakh in early 1920, stipulating their acceptance of permanent inclusion into Azerbaijan. Leaders associated with the Republic of Mountainous Armenia and the Dashnak Party attempted to organize a rebellion against Azerbaijani rule, which failed and led to the massacre and displacement of Shusha's Armenian population. By 1921, Soviet authorities were in control of Nagorno-Karabakh who decided on the formation of the Nagorno-Karabakh Autonomous Oblast (NKAO) within Soviet Azerbaijan.
In 1964, the Armenians of Karabakh sent a letter to leader of the USSR, Nikita Khrushchev, complaining about Azerbaijan's economic management of the region. They also requested that the NKAO and adjacent regions where the Armenian population is approximately 90% be reincorporated into the Armenian SSR or integrated into the RSFSR. The Nagorno-Karabakh Armenian intellectuals who wrote to the Kremlin were imprisoned, put under surveillance, or forced to leave Nagorno-Karabakh. All lost their jobs and were removed from the Communist Party.
I tried to change the demographics in Karabakh. We encouraged Azeris living in neighbouring regions to move to Karabakh instead of to Baku. I made efforts to ensure that there would be more Azerbaijanis and less Armenians living there.
Throughout the Soviet period, Azerbaijani authorities implemented policies aimed at diluting the Armenian majority in Nagorno-Karabakh through various means, including border manipulations, encouraging the exodus of Armenians, and settling Azerbaijanis in the region. Census data from the Soviet period reflects these demographic shifts. Shusha—once a major center of Armenian cultural life—became overwhelmingly Azerbaijani. In the 1920s, Armenians constituted 94.4% of Nagorno-Karabagh’s population, with only 5.6% being Azerbaijani; by 1979, Armenians' share had fallen to 76%, while the share of Azerbaijanis had increased to 24%.
This discrimination against the Armenian population was part of a part of a broader strategy to suppress Armenian culture and identity in Nagorno-Karabakh. Former Azerbaijani President Heydar Aliyev later admitted to supporting some of these policies. Teaching Armenian history in Nagorno-Karabakh was banned. Nagorno-Karabakh Armenians were persecuted for choosing to attend college in Armenia instead of Azerbaijan or for supporting the FC Ararat Yerevan football club instead of Neftchi Baku. The 1973 Soviet Top League final in which Ararat Yerevan defeated FC Dynamo Kyiv was not aired in Azerbaijan SSR, and Nagorno-Karabakh Armenians that listened to the match by radio were arrested and questioned by the KGB. Despite these pressures, Armenians remained the majority in Nagorno-Karabakh when the USSR collapsed.
Amid Mikhail Gorbachev's reforms the dissolution of the Soviet Union in 1988–89, a 1988 Nagorno-Karabakh referendum was held to transfer the region to Soviet Armenia, citing self-determination laws in the Soviet constitution. In response, a series of pogroms were committed against Armenians throughout Azerbaijan, leading to the start of the Nagorno-Karabakh War. Professor Matt Qvortrup considered it hypocritical that Western Europe countries had eagerly recognised the succession of several states from Yugoslavia, ignoring the laws of territorial integrity, but simultaneously did not show the same interest for the Nagorno-Karabakh referendum, noting "the practice of independence referendums seemingly owes more to national interest than to adherence to principles of jurisprudence".
According to Stuart Kaufman, a professor of political science and international relations, and de Waal, the first instance of violence in the conflict occurred in October 1987 when an Azerbaijani official "punished" the Armenian-populated village of Chardakhly with a raid for protesting against the appointment of a new collective-farm director. During the raid, the village's women, children, and elderly were beaten up. In his 2003 book Black Garden, de Waal speculated that "[p]ossibly in reaction to such incidents", Azerbaijanis in Armenia (specifically in the districts of Ghapan and Meghri) were in November 1987 driven out of their homes, arriving at Baku in two freight cars. A number of Armenian scholars and investigative journalists, however, have scrutinized these alleged incidents and argued that, outside the claims made by Azerbaijani officials, there is no evidence, archival or otherwise, to corroborate such instances of mass violence taking place, at least prior to February 1988.
Timeline
First Nagorno-Karabakh War (1988–1994)
The First Nagorno-Karabakh War, also known as the Artsakh Liberation War in Armenia and Nagorno-Karabakh, was an armed conflict that took place in the late 1980s to May 1994, in the enclave of Nagorno-Karabakh in southwestern Azerbaijan, between the majority ethnic Armenians of Nagorno-Karabakh backed by the Republic of Armenia, and the Republic of Azerbaijan. As the war progressed, Armenia and Azerbaijan, then both former Soviet Republics, entangled themselves in a protracted, undeclared war in the mountainous heights of Karabakh as Azerbaijan attempted to curb the Armenian Karabakh movement.
On 20 February 1988, the enclave's parliament voted 110-17 in favor of uniting with Armenia. The demand to unify with Armenia, which began anew in 1988, began in a relatively peaceful manner. As the Soviet Union's dissolution neared, the tensions gradually grew into an increasingly violent conflict between ethnic Armenians and ethnic Azerbaijanis. Both sides made claims of ethnic cleansing and pogroms conducted by the other.
The circumstances of the dissolution of the Soviet Union facilitated an Armenian secessionist movement in Soviet Azerbaijan. As Azerbaijan declared its independence from the Soviet Union and removed the powers held by the enclave's government, the Armenian majority of Nagorno-Karabakh voted to secede from Azerbaijan. The referendum held in 1991 was boycotted by the Azerbaijani population and had an electorate turnout of 82.1%, of which 99.9% voted in favor of independence. The referendum resulted in the unrecognized Republic of Nagorno-Karabakh.
Full-scale fighting erupted in the late winter of 1992. International mediation by several groups, including the Organization for Security and Co-operation in Europe (OSCE), failed to bring resolution. In the spring of 1993, Armenian forces captured territory outside the enclave itself, threatening to catalyze the involvement of other countries in the region. By the end of the war in 1994, the Armenians were in full control of most of the enclave and also held and currently control approximately 9% of Azerbaijan's territory outside the enclave. An estimated 353,000 Armenians from Azerbaijan and 500,000 Azerbaijanis from Armenia and Nagorno-Karabakh were displaced as a result of the conflict. A Russian-brokered ceasefire was signed in May 1994, leading to diplomatic mediation.
Border clashes (2008–2020)
The 2008 Mardakert clashes began on 4 March after the 2008 Armenian election protests, resulting in several score wounded and killed, with both sides declaring victory. It was the heaviest fighting between ethnic Armenian and Azerbaijani forces since the 1994 ceasefire after the First Nagorno-Karabakh War. Following the incident, on 14 March the United Nations General Assembly by a recorded vote of 39 in favour to 7 against adopted Resolution 62/243, demanding the immediate withdrawal of all Armenian forces from the occupied territories of Azerbaijan. The 2010 Nagorno-Karabakh clash was a scattered exchange of gunfire that took place on 18 February on the line of contact dividing Azerbaijani and the Karabakh Armenian military forces. As a result, three Azerbaijani soldiers were killed and one wounded. The 2010 Mardakert clashes were the deadliest for Armenian forces since the 2008 violence. Between 2008 and 2010, 74 soldiers were killed on both sides.
In late April 2011, border clashes left dead three Artsakh Defence Army soldiers, while on 5 October, two Azerbaijani and one Armenian soldier were killed. In all during the year, 10 Armenian soldiers were killed. The following year, continued border clashes between the armed forces of Armenia and Azerbaijan took place from late April through early June. The clashes resulted in the deaths of five Azerbaijani and four Armenian soldiers. In all during 2012, approximately 20 Azerbaijani and 14 Armenian soldiers were killed. Throughout 2013, 12 Azerbaijani and 7 Armenian soldiers were killed in border clashes.
In 2014, several border clashes erupted. By August, 27 Azerbaijani soldiers had died since the start of the year. On 12 November 2014, the Azerbaijani armed forces shot down a Nagorno-Karabakh Defense Army Mil Mi-24 helicopter over Karabakh's Agdam district. With the crash, 2014 became the deadliest year for Armenian forces since the 1994 ceasefire agreement, with 27 soldiers killed. Six Armenian civilians also died in 2014, while by the end of the year the number of Azerbaijanis killed rose to 39 (37 soldiers and 2 civilians). In 2015, 42 Armenian soldiers and 5 civilians were killed as border clashes continued. In addition, at least 64 Azerbaijani soldiers also died, according to Armenian sources.
Over the years, propelled by oil and gas revenues, Azerbaijan embarked in a military build-up. In 2015 alone, Baku spent US$3 billion on its military, more than Armenia's entire national budget.
In early 2016, the most serious clashes until the 2020 war occurred (the 2016 Nagorno-Karabakh conflict). Between 1 and 5 April 2016, heavy fighting along the Nagorno-Karabakh frontline left 88 Armenian and 31–92 Azerbaijani soldiers dead. One Armenian and three Azerbaijani soldiers were also missing. In addition, 10 civilians (six Azerbaijani and four Armenian) were also killed. During the clashes, an Azerbaijani military helicopter and 13 unmanned drones were shot down and an Azerbaijani tank was destroyed, while Nagorno-Karabakh lost 14 tanks.
Continued clashes occurred in 2018. Three civilian volunteers were killed in a demining operation in Nagorno-Karabakh on 29 March 2018. 2020 saw a number of clashes, particularly heavy in July (July 2020 Armenian–Azerbaijani clashes).
Second Nagorno-Karabakh War (2020)
Large-scale fighting began on the morning of 27 September, with an Azerbaijani offensive along the line of contact established in the aftermath of the first war. Clashes were particularly intense in the less mountainous districts of southern Nagorno-Karabakh. On the same day, Azerbaijan's Parliament declared a martial law and established curfews in several cities and regions following the clashes. Turkey provided military support to Azerbaijan, although the extent of this support is disputed.
The war was marked by the deployment of drones, sensors, long-range heavy artillery and missile strikes, as well as by state propaganda and the use of official social media accounts in online information warfare. Azerbaijan's widespread use of drones was seen as crucial in determining the conflict's outcome. Numerous countries and the United Nations strongly condemned the fighting and called on both sides to de-escalate tensions and resume meaningful negotiations. Three ceasefires brokered by Russia, France, and the United States failed to stop the conflict.