SUMMARY
Nagorno-Karabakh is a region in Azerbaijan, and the legitimate belonging of Nagorno-Karabakh is a long-disputed question. Following the fall of the Soviet Union and the independence of Azerbaijan in 1991, the conflict intensified between Armenia-supported Republic of Artsakh and the Government of Azerbaijan. Though several ceasefire agreements put a halt to the conflict for a while, the incompatibility was not solved, and sporadic clashes continued. Talks between the parties took place occasionally. Nevertheless, no agreement was reached, and the exchanges of fire and ceasefire violations along the ceasefire line were a reoccurring feature of the conflict throughout the years until late 2023.
For a second consecutive year, UCDP recorded no organized violence in Azerbaijan in 2025. With the Azerbaijan: Artsakh conflict terminated, the year was shaped instead by the peace process with Armenia. In March 2025, Azerbaijan and Armenia announced that they had agreed on the full text of a peace treaty. On 8 August 2025, at a summit in Washington hosted by United States President Donald Trump, the two countries' foreign ministers initialed the agreed text, but Presidents Ilham Aliyev and Prime Minister Nikol Pashinyan did not sign the treaty itself, signing instead a joint declaration committing to work toward its eventual signing and ratification, alongside bilateral agreements with the United States that included a planned transit route through Armenia's Syunik region, the Trump Route for International Peace and Prosperity, connecting Azerbaijan with its Nakhchivan exclave. The two sides also called for the dissolution of the OSCE Minsk Group, which the OSCE moved to disband. The treaty remained unsigned and unratified at year's end, with Baku demanding that Armenia amend its constitution to remove what it regarded as implicit claims to Nagorno-Karabakh.
IN DEPTH
The conflict in the Soviet era and newly independent Azerbaijan
Nagorno-Karabakh is a region in Azerbaijan populated mainly by Armenians. The legitimate belonging of Nagorno-Karabakh is a long-disputed question. At the beginning of the 20th century, Nagorno-Karabakh was a part of Armenia, but in the 1920s, it was decided that the area was to belong to Azerbaijan. During the Soviet era, the underlying conflict in the area was suppressed. The conflict re-emerged at the end of the 1980s. In February 1988, the regional council in Nagorno-Karabakh voted that the region should be integrated into Armenia. Subsequently, Moscow imposed a direct rule over the territory, but as soon as this was ended in November 1989, Armenia declared the enclave to be part of a unified Armenian republic. Armenia fought with the USSR over Nagorno-Karabakh for two years. For more information, see the Russia (Soviet Union): Nagorno-Karabakh conflict page.
The disappearance of one of the conflict parties as to the Soviet Union dissolved at the end of 1991 did not solve the conflict. Instead, the dispute about Nagorno-Karabakh's status remained infected inside newly independent Azerbaijan as Nagorno-Karabakh proclaimed itself an independent republic. The conflict became even more intense than before, with thousands of deaths in the following three years. The difference before and after the collapse of the Soviet Union was that instead of Armenia fighting Moscow over the rightful belonging of the enclave, the Republic of Nagorno-Karabakh, with the help from Armenia, now fought the state it was a part of, Azerbaijan, to win independence. The Azerbaijani leadership responded to Nagorno-Karabakh's proclamation by imposing a direct presidential rule over the region.
Although having fought for Nagorno-Karabakh's inclusion into Armenian territory for two years, and having expressed support for Nagorno-Karabakh's demand of independence on 3 January 1992, the Armenian president made an announcement in March 1992 declaring that the status of Nagorno-Karabakh was an internal matter of Azerbaijan. Thus, the problem was to be solved by Azerbaijan only. However, despite repeated denials of its involvement, it is evident that Armenia remained involved in the conflict over Nagorno-Karabakh after 1992.
During the course of the conflict, negotiations have been held on several occasions, most of the time under the auspices of the Organisation on Security and Cooperation in Europe, OSCE (previously known as CSCE, Conference on Security and Cooperation in Europe), but peace talks were also mediated by, among others, the United Nations after 1993. Despite efforts to solve the conflict and ceasefire agreements/attempts nearly every month during 1993, it was not until 1994 that the conflict took a positive turn. After negotiations in Moscow in May 1994 with Commonwealth of Independent States (CIS) delegates, the chair of the National Assembly in Azerbaijan signed a protocol calling for a ceasefire and the deployment of international peacekeeping forces the same month. The agreement was given legal status and was extended indefinitely on 27 July by the Defense Ministers of Armenia and Azerbaijan and the military leader of Nagorno-Karabakh. A series of violent incidents and rallies by groups opposed to the agreement took place during the remaining months of the year.
As a result of the conflict, the Armenia-backed Nagorno-Karabakh authorities had gained de facto control over the Nagorno-Karabakh region and substantial Azerbaijani territories, including most of the strategic heights around Nagorno-Karabakh. The relationship between the sides to the conflict remained tense in the following years, with no political solution within reach.
Slow progress in negotiations and increasing tensions (1994–2015)
Organized negotiations over a solution to the conflict started as early as 1992 when OSCE was involved. In the early years of mediation, much of the organizational efforts went towards finding a working format for talks between the eleven participating countries. The original mediation format turned out to be too cumbersome, and after narrowing the format by creating a smaller subset group, the negotiations were able to move on. The smaller subset group under the OSCE umbrella is called the Minsk group and has three co-chairs; Russia, France, and the US. Representatives of Nagorno-Karabakh were not included due to Azerbaijan’s objections and due to the fact that the enclave was never formally recognized as a sovereign state by any country, including its closest ally Armenia. Armenia functioned as a stand-in for Nagorno-Karabakh at the negotiating table. This function came with the understanding that Armenia wielded considerable power over the leadership of Nagorno-Karabakh, which relied on Armenia for both political and military support.
Although part of the Minsk group, Russia brokered a ceasefire agreement called the Bishkek protocol in 1994, mainly acting on its own authority. The agreement resulted in the establishment of a self-regulating ceasefire line referred to as the Line of Contact (LoC). The LoC stretched for 110 miles and separated the armed forces of Azerbaijan and Nagorno-Karabakh. There had been substantial fortifications built along the line, and the area was both mined and filled with underground tunnels. The LoC remained a focus for immediate security concerns as most casualties during ceasefire violations were connected to exchanges of fire along this line. The line was also at the focus of the negotiations as it was connected to the seven adjacent districts occupied by Nagorno-Karabakh.
After the ceasefire agreement and under the aegis of the Minsk group, the negotiations started to move ahead slowly. In 1996, the Lisbon summit outlined the basis for the first proposal; Nagorno-Karabakh was to be given autonomy while Azerbaijan’s territorial integrity was to be kept intact. Azerbaijan supported the proposal, as did all other OSCE members except for Armenia. Armenia vetoed the proposal objecting to the fact that the status of Nagorno-Karabakh would be decided before any comprehensive settlement over the conflict had been reached.
In 1997 and 1998, the conflict intensified, and tensions rose as violent clashes along the LoC resulted in an increased number of battle-related deaths. During these years, the Minsk group presented several proposals, one of which entailed a phased approach and one which entailed the common state approach. In October 1997, the co-chairs put forward the proposal with a phased approach, which meant that all but one component of the peace settlement would be implemented in a first step while the second step would address the last component, the status of Nagorno-Karabakh. The proposal was accepted by the presidents of Azerbaijan and Armenia but decisively rejected by the Nagorno-Karabakh leadership. The rejection of the proposal along with domestic critique against the Armenian President Ter-Petrosyan for accepting it led to a drastic shift in Armenian government which changed the conditions for the peace talks. The new Armenian President Kocharyan, a former leader of Nagorno-Karabakh, took a more rigid stand in the negotiations, which were caught in an impasse. In November 1998, in an attempt to break the stalemate, the Minsk Group presented a proposal using the common state approach, which broke the pattern of all previously suggested proposals. The approach meant that the conflicting parties, an enclave and a state, would be considered equals in creating a common state or a confederation. The proposal was controversial not only because it left the status of Nagorno-Karabakh vague, but also it seemed to sidestep the principle of territorial integrity. Armenia and Nagorno-Karabakh accepted the proposal, while it drew hard criticism from Azerbaijan, which rejected it on the basis that it compromised the OSCE’s owns founding principles.
At the beginning of 1999, under the Clinton administration, the US tried to inject new impetus into the mediation process. The presidents of Azerbaijan and Armenia met several times during the year, beginning in April in Washington. Towards the end of the year, in October, the conditions for peace talks changed dramatically. Gunmen stormed into the Armenian parliament, shooting and killing several members of the parliament, including the Armenian Prime Minister Sargsian. The details of the proposal discussed previous to the attack remain unclear, but it entailed a land swap, the Nagorno-Karabakh enclave against the Azerbaijani exclave of Nakhichevan. The proposed swap would have shifted the borders of Azerbaijan and Armenia. However, the attack effectively overshadowed any peace talk efforts and drew attention to the dissent within Armenia and the difficulty of balancing domestic demands and long-term strategies.
Between 2000 and 2004, the intensity of the conflict remained on a low level despite sporadic clashes on the LoC and, although fragile, the ceasefire was holding. Despite continuous efforts by the mediators, no progress was made, and the negotiations were stalling. In 2004, the Minsk group sought to secure a new open framework for negotiations and therefore initiated the Prague Process. The foreign ministers of Azerbaijan and Armenia were to meet on a regular basis. These meetings would be less restricted by predefined conditions and pave the way for presidential meetings. In 2005, the conflict began once again to intensify, and the numbers of casualties along the ceasefire line began to increase. Rich from oil exports and having increased its military spending exponentially, Azerbaijan asserted its right to win back Nagorno-Karabakh by force. In 2006, despite the increase in tension, the Minsk group pushed ahead and developed plans for a new comprehensive settlement.
In November 2007, the three co-chairs of the Minsk group put forward a new proposal based on what was called the Madrid principles. The proposal, to some extent, represented a return to the primary goal of securing both the right to self-determination for Nagorno-Karabakh and protecting Azerbaijan’s territorial integrity. The proposal was structured around a phased approach and, in a first step, stipulated the withdrawal of Nagorno-Karabakh forces from occupied districts and a demilitarization of the area. The second step would involve the return of Azerbaijani refugees while providing security guarantees and an interim status for Nagorno-Karabakh until the conditions for a referendum had been agreed upon. In 2008, the conflict started to intensify as violations against the ceasefire increased the number of battle-related deaths, and a belligerent tone permeated the official communication between Azerbaijan and Armenia. The diplomatic efforts were stepped up, and in 2009, the presidents of Armenia and Azerbaijan met a record number of times in a single year. By 2010, the President of Azerbaijan announced that he essentially agreed to the proposal, but the negotiations began to stall as the Armenian President came under pressure by sharp domestic critique and opposition from the Armenian diaspora. By 2011 negotiations had ended in a deadlock, and even though the presidents of Azerbaijan and Armenia had continued to meet in the following years, no substantial progress had been made.
Overall the years between 2008 and 2015 saw increasingly vitriolic rhetoric surrounding the conflict, and Azerbaijan and Armenia were drawn into an arms race while both sides also staged war games. During this period, there were also reports of the use of mortars and not just small arms as in previous years. On the LoC, both Azerbaijani troops and the Nagorno-Karabakh troops gradually moved their positions and fortifications closer. According to some reports, in some places, the distances between the forces were just twenty to forty meters, which substantially increased the risk of an accidental return into full-scale use of armed force. In 2014 there was an upsurge in violence, and clashes resulted in the highest number of battle-related deaths since 1994. In December 2015, the presidents of Azerbaijan and Armenia met in Switzerland for talks on the conflict in Nagorno-Karabakh.
The 2016 Escalation and Aftermath
In early April 2016, violence unexpectedly escalated along the LoC, separating Karabakh-Armenian and Azerbaijani forces. While ceasefire violations and minor clashes had been endemic along the LoC, and while there had occasionally been more severe bouts of violence, the events in April quickly developed into the worst fighting since the 1994 ceasefire. The Azerbaijani army launched concurrent offensives against two strategic points along the LoC: in the northeastern sector close to the town Martakert and in the southern sector at Jabrayil, near the Iranian border. The Republic of Nagorno-Karabakh’s armed forces were seemingly unprepared for a large-scale attack, and the Azerbaijani army broke through their lines; Azerbaijan also deployed artillery and rockets against Armenian villages in Nagorno-Karabakh to increase the confusion among the defenders. The fighting was far more intense than the “normal” ceasefire violations seen along the LoC, which usually involved small arms fire and sporadic shelling, as both sides deployed large numbers of armored vehicles, heavy artillery, “suicide” drones, and multiple rocket launchers.
The Azerbaijani attack was initially successful, and for the first time since the 1990s, Azerbaijan successfully captured territory occupied by the Republic of Nagorno-Karabakh. After a few days, the Nagorno-Karabakh armed forces were able to regroup, which prompted Azerbaijani President Ilham Aliyev to call off the offensive; continued fighting in inaccessible, well-defended terrain was deemed too costly. Nevertheless, Azerbaijan successfully captured a number of strategic locations during the days of fighting. More than 100 people, both soldiers and civilians, were killed in the fighting. The relatively short period of intensified violence also prevented a broader escalation of the conflict; at the height of the escalation, it appeared as if an open conflict between Armenia, the Republic of Nagorno-Karabakh’s most staunch ally, and Azerbaijan was imminent. For example, when Azerbaijan threatened to strike Stepanakert, the de facto capital of the Republic of Nagorno-Karabakh, Armenia responded by threatening attacks against targets in Azerbaijan. However, regular Armenian forces never engaged directly in combat against Azerbaijan, even if a large number of Armenian soldiers served in the Nagorno-Karabakh armed forces. The risk of a wider conflict was also mitigated by the Government of Azerbaijan’s decision not to attack any targets near the internationally recognized border with Armenia, and instead concentrating its attacks to areas along the LoC.
The international response to the fighting was immediate. For example, the President of Russia, Vladimir Putin, called for both parties to cease hostilities already on 2 April. Russia also pressured both the Armenian and Azerbaijani foreign and defense ministries to end the hostilities. The OSCE, EU, and Germany also issued statements denouncing the violence. Nevertheless, Russia applied the most intensive pressure, and on 5 April, President Putin spoke to both the Armenian and Azerbaijani presidents. A quick de-escalation was then achieved after a meeting between the Armenian and Azerbaijani chiefs of staff in Russia. However, there were no signs that a permanent negotiated settlement of the conflict was imminent through the rest of 2016 and 2017. International (mainly Western) engagement in settlement efforts had waned considerably in the years leading up to the escalation; the OSCE “Minsk Group” charged with facilitating negotiations had also been largely unsuccessful. The only actor actively engaging the parties was Russia, which had extensive bilateral ties to the conflict parties.
Nevertheless, it remained uncertain to what extent Russian involvement could achieve a mutually acceptable solution. The fighting in 2016 also further entrenched hostile attitudes among the broader Armenian and Azerbaijani populations; there was also a significant increase of hostile rhetoric used by top political leaders in both Azerbaijan and Armenia. As such, the fighting in 2016 significantly damaged the relations between the conflict parties.
Azerbaijan’s relative military success, which led to a marked increase in the public approval of President Aliyev, emboldened the Azerbaijani regime. Drawing parallels to the Russian annexation of Crimea in 2014 and involvement in the conflict in eastern Ukraine, Azerbaijan raised its legal demands, calling for the international community to take tougher, coercive action against the Armenian “annexation” of Nagorno-Karabakh. In Nagorno-Karabakh, one of the most direct reactions to the 2016 fighting was a referendum on the breakaway republic’s constitution on 20 February 2017. Aside from changes in the political system, the most conflict-related consequence of the referendum was the official change of the republic’s name from the “Republic of Nagorno-Karabakh” to the “Republic of Artsakh”. The old name “Nagorno-Karabakh” had been a mix of Russian and Turkic, meaning “Mountainous Karabakh,” while “Artsakh” is Armenian. Furthermore, “Artsakh” also implied a broader territorial claim, as it also referred to the territories occupied by the breakaway republic outside of Nagorno-Karabakh proper (that is, the territories on the Armenian-controlled side of the LoC).
The 2020 Escalation and the Second Nagorno-Karabakh War
After minor violations of the ceasefire in the early months of 2020, the Government of Azerbaijan and Republic of Artsakh clashed in multiple locations in July. The fighting occurred mainly near the Tovuz district of Azerbaijan. The tension did not deescalate during the summer, with both sides importing weaponry and accusing each other.
On 27 September, clashes erupted at the LoC and immediately turned into a major Azerbaijani offensive along the entire front line. Azerbaijani President Aliyev announced his willingness to retake all occupied territories and accept a ceasefire only when Armenian forces withdraw from Nagorno-Karabakh. The Government of Turkey supported Azerbaijan and though officially denied, multiple sources affirmed that Turkey transferred Syrian mercenaries to Nagorno-Karabakh from the conflict in Syria. Russia, a historical Armenian ally, declared that it would have intervened only if the fightings reached Armenia. Azerbaijan quickly took the upper hand in the clashes, thanks to its military capabilities increased by importing drones from Israel and Turkey. The support by Armenian volunteers was not sufficient for the forces of the Republic of Artsakh. On 5 October, Azerbaijani forces overran Artsakh's defense lines in the most southern part of the LoC, where the territory is less mountainous and thus more suitable for offensives. On 7 October, the first strategic village, Jabrayil, was captured by the Azerbaijani forces. Fightings for the provincial capital of Hadrut began soon after, with the town ended up in Azerbaijani hands on 16 October. Then, Fuzuli was captured. At that point, the Azerbaijani army attacked mainly in two directions: one through the mountains north of Hadrut in the direction of Shushi/Shusha and Khankendi/Stepanakert, and the other towards Armenia along the border with Iran. On 22 October, the whole border with Iran was in Azerbaijani hands for the first time after decades. Following that objective, the troops moved north to cut the vital Lachin corridor, which connects Armenia with the Artsakh's de facto capital of Khankendi/Stepanakert. After intense fighting, on 8 November, President Aliyev announced the capture of Shushi/Shusha.
On 9 November, the Government of Azerbaijan accidentally shot down a helicopter belonging to the Russia and killed two soldiers. Following this incident, Russia managed to broker a ceasefire agreement, ending the clashes. This was the third attempted ceasefire agreement and the first one to be successful. Armenia, on behalf of the Republic of Artsakh, agreed on the Azerbaijani control over the areas that Azerbaijani forces took over during the conflict and also agreed to withdraw from the territories that Armenian forces occupied around the Nagorno-Karabakh. The Republic of Artsakh kept de facto control over the parts of Nagorno-Karabakh that were not captured by Azerbaijani forces at the moment of the ceasefire, with Russian peacekeepers separating the two sides and maintaining order. Peacekeepers from Turkey also soon arrived and took part in this process. The war resulted in nearly 8 thousand battle-related deaths. Hundreds of civilians died, mainly due to the shelling of inhabited centers by both sides.
Following the 2020 Nagorno-Karabakh War, the Azerbaijan: Artsakh conflict entered a calmer period in 2021. Though the conflict remained active primarily due to some sporadic border clashes around Azerbaijan's Kelbajar rayon and Armenia's Gegharkunik province, the conflict intensity was much lower than what it was in 2020. Several violations of the November 2020 ceasefire were observed throughout the year, though the conflict did not escalate further.
In 2021, more than a dozen civilians were killed by landmines. These were mostly located in the areas under the control of the Armenian forces before the war. Meanwhile, there had been several talks between Azerbaijan and Armenia, on behalf of the Republic of Artsakh, following the calls of the OSCE Minsk Group and the European Union.
Tensions persisted in 2022 between Azerbaijan and Armenia, with reciprocal allegations of shooting along the border throughout the year. Notably, on 12 September 2022, hostilities significantly intensified, resulting in over 300 battle-related deaths in just two days. To prevent further escalation, Russia intervened in the conflict, ultimately resulting in a ceasefire being reached between Armenia and Azerbaijan on 14 September 2022.
In 2023, the Azerbaijan: Artsakh conflict escalated significantly, resulting in around 450 fatalities within just two days. On September 19, Azerbaijan launched a military offensive against the self-declared Republic of Artsakh to disarm the Artsakh forces and ensure their surrender. A ceasefire was brokered the following day by Russia, leading to the agreement that the Artsakh forces would be disarmed. The ceasefire agreement also led to the announcement that the Republic of Artsakh would cease to exist from January 1, 2024, terminating the Azerbaijan: Artsakh conflict.
In 2024, the landscape of organized violence in Azerbaijan was heavily influenced by the fragile peace process with Armenia. The dissolution of the Republic of Artsakh solidified Baku’s control over the region and shifted the realities on the ground, though questions remained about the future of displaced populations and the rights of ethnic Armenians in the area. The dissolution also paved the way for a renewed push toward peace, with both sides showing greater willingness to engage in direct negotiations.
In 2025, for a second consecutive year, UCDP recorded no organized violence in Azerbaijan. With the Azerbaijan: Artsakh conflict terminated, the year was shaped instead by the peace process with Armenia. In March 2025, Azerbaijan and Armenia announced that they had agreed on the full text of a peace treaty. On 8 August 2025, at a summit in Washington hosted by United States President Donald Trump, the two countries' foreign ministers initialed the agreed text, but Presidents Ilham Aliyev and Prime Minister Nikol Pashinyan did not sign the treaty itself, signing instead a joint declaration committing to work toward its eventual signing and ratification, alongside bilateral agreements with the United States that included a planned transit route through Armenia's Syunik region, the Trump Route for International Peace and Prosperity, connecting Azerbaijan with its Nakhchivan exclave. The two sides also called for the dissolution of the OSCE Minsk Group, which the OSCE moved to disband. The treaty remained unsigned and unratified at year's end, with Baku demanding that Armenia amend its constitution to remove what it regarded as implicit claims to Nagorno-Karabakh.
