This is an account of engagements which occurred during the Second Nagorno-Karabakh War, primarily based on announcements from the belligerents. The war has been characterized by the use of armoured warfare; drone warfare, especially the use of Turkish-made Bayraktar TB2 and Israeli loitering munition Harop drones; heavy artillery; rocket attacks; and trench warfare. It has also featured the deployment of cluster munitions, which are banned by the majority of the international community but not by Armenia or Azerbaijan: Azerbaijan states that Armenia has deployed cluster munitions against civilians, and international third parties have confirmed evidence of Azerbaijan's use of cluster munitions against civilian areas of Nagorno-Karabakh. A series of ballistic missile attacks have inflicted mass civilian casualties in Ganja, Azerbaijan, while civilian residences and infrastructure in Stepanakert, and elsewhere have been targeted, inflicting casualties and causing extensive damage.

The conflict is also marked by extensive social media campaigning - some of which is alleged to be "inauthentic" - and widespread misinformation, exacerbated by the low number of journalists that have access to the frontline. This phenomenon has been characterized as an information war concurrent to the physical battles on the ground. Facebook has claimed to have removed a number of Facebook and Instagram accounts and pages that were involved in "co-ordinated inauthentic behavior".

The amount of territory contested is relatively restricted, but the war has expanded beyond the borders of Nagorno-Karabakh due to the level of conflict and kind of munitions deployed and spilled over international borders. Shells and rockets have landed in East Azerbaijan Province in Iran, although causing no damage, and Iran has reported several unmanned aerial vehicles (UAVs) downed or crashed within its territory, while Georgia stated that two UAVs had crashed in Kakheti Province.

After the shelling of Khojavend, Artsakh authorities began mobilizing civilians. Just before 04:00 (00:00 GMT) on 10 October, Russia reported that both Armenia and Azerbaijan had agreed on a humanitarian ceasefire after ten hours of talks in Moscow (the Moscow Statement) and announced that both would enter "substantive" talks. Fighting continued: a second ceasefire attempt midnight 17 October was also ignored, followed by a third ceasefire attempt failing on 26 October.

A ceasefire agreement was signed by the governments of Azerbaijan, Armenia and Russia on 9 November 2020, bringing the conflict to a close.

September

27 September

According to Artsakh authorities, hostilities commenced when at 08:03 Azerbaijani armed forces launched artillery and aerial strikes against civilian settlements, including the capital, Stepanakert. The Armenian Ministry of Defence (MoD) stated that the Azerbaijani offensive, aimed at Stepanakert, began at 08:10 local time (04:10 GMT). Azerbaijani authorities stated that at about 06:00 local time, Armenian armed forces started intensive shelling of Azerbaijani army positions along the entire front and of nearby Azerbaijani settlements. Azerbaijan thus stated that it launched a counteroffensive. In the offensive, Azerbaijan stated it deployed manpower, tank and rocket artillery units, aircraft and UAVs. The Republic of Artsakh introduced martial law and total mobilization of its male population, while the Azerbaijani President addressed the nation.

In the afternoon, Azerbaijan announced martial law and a curfew. The Azerbaijani military deployed tanks, artillery, missile systems and aircraft near the front and entered deeper into Nagorno-Karabakh. According to the Armenian MoD, in the morning Azerbaijani armed forces also attacked in the direction of Vardenis in Armenia proper. The Azerbaijani MoD stated it had taken seven villages in Nagorno-Karabakh. At 16:29, Azerbaijan issued a surrender ultimatum to the Armenian command in the zone, while affirming its compliance with international humanitarian law and the Geneva Conventions. In the afternoon, the Azerbaijani MoD stated it had taken a mountain peak in the Murovdag range. The Ministry also stated that its forces had taken effective control of the Vardenis–Martakert/Aghdara highway connecting Nagorno-Karabakh and Armenia.

28 September

At around 08:00, the Azerbaijani MoD stated that Armenian forces had fired upon Tartar in the early morning and issued a warning in response, while the Azerbaijani Ministry of Foreign Affairs (MoFA) stated that Armenian forces had purposefully targeted civilian sites and civilians. The President of Artsakh stated that during the morning's clashes, Armenian forces had regained control over a number of previously ceded positions. At approximately 10:00, the Azerbaijani MoD said that Azerbaijani forces had gained strategic high ground around Talış while Armenian forces had incurred heavy losses. The President of Artsakh stated that Azerbaijani forces were facing Armenian attacks on all fronts. Shortly after, the Azerbaijani MoD stated that Azerbaijani forces had fired on Armenian artillery units that had been targeting Azerbaijani-controlled settlements in the area of Aghdara; it added Armenian units had incurred losses from artillery fire and withdrew.

At around 19:00, the Azerbaijani MoD stated that Armenian forces had fired upon Yuxarı Ağcakənd and Qaramusalı in Goranboy District. At approximately 20:00, Artsakh authorities stated that Armenian forces had retaken some positions, adding that Armenian forces had repelled Azerbaijani attacks and advanced into Azerbaijani territory. Subsequently, at approximately 21:00, an Armenian MoD-related source, Artsrun Hovhannisyan, stated that Azerbaijani forces had launched a new major offensive operation in the Aras Valley and in the direction of Madagiz–Talış. Around one hour later, Poghosyan stated that an Azerbaijani airplane had been shot down near Khojavend; Azerbaijan issued a denial. The Azerbaijani MoD denied allegations that Azerbaijan had deployed F-16s, denying it owned any.

29 September

At around 08:00, the Azerbaijani MoD stated that intensified clashes had continued along the front overnight; it added it had repelled an Armenian counterattack. Concurrently, Azerbaijani aerial and ground forces allegedly destroyed a mixed column of Armenian military vehicles travelling from Madagiz in the direction of Aghdara, together with an artillery battery. At approximately 09:00, the Ministry stated that from 07:30, Azerbaijan's Dashkasan District had been shelled from Vardenis, in Armenia; the Armenian MoFA issued a denial, saying this was a fabrication to justify expanding the theater of operations, including against Armenia. Azerbaijani authorities reiterated its statements of Armenian aggression. The Azerbaijani MoD then stated that its offensive on Fuzuli City continued from the early morning. Subsequently, it denied Armenian reports of retaking territory.

At around 11:00, the Armenian MoD stated that Azerbaijani forces had fired on the Armenian military base in Vardenis, within Armenia, also deploying its air force. The Azerbaijani MoD said they destroyed an Armenian motorized rifle regiment stationed in Khojavend District; the ADA issued a denial. Azerbaijan stated it had destroyed an Armenian Uragan multiple rocket launcher in Khojavend District. Subsequently, an Armenian source said further Azerbaijani attacks were repelled.

At around 12:00, one Azerbaijani gunship was said to have been downed; the Azerbaijani MoD issued a denial, stating it had not been deploying helicopters. At approximately 12:40, ADA units reported to have downed two helicopters using Igla man-portable surface-to-air missiles; Artsakh released footage apparently showing this. An Armenian source then stated that Azerbaijani forces were bombarding areas near Vardenis. The Azerbaijani MoD stated it had destroyed an Armenian command-and-observation post in Hadrut in Khojavend District, while the Armenian MoD announced it would be deploying heavier weapons and was repelling Azerbaijani offensives.

The Azerbaijani MoD stated that an Armenian attempt to assault Azerbaijani-controlled military positions from Aşağı Veysəlli in Fuzuli District had been repelled, with Armenian losses. At approximately 13:20, the Armenian MoD stated that the Azerbaijani military had launched an offensive. Around two hours later, the Azerbaijani MoD stated that S-300 missile systems defending Yerevan's airspace were being redeployed towards Nagorno-Karabakh and would be targeted. Shortly after, the ADA released footage apparently showing Armenian forces downing an Azerbaijani gunship.

At around 18:00, the Artsakh MoD stated that Azerbaijani forces had attacked along the northern and north-eastern directions of the front, while the ADA had inflicted losses. Shortly after, the Armenian MoD stated that a Turkish F-16, taking off from Ganja International Airport had downed an Armenian Su-25, killing the pilot. Both Azerbaijani and Turkish authorities issued denials; the Armenian MoD released images of a wrecked Su-25. According to Azerbaijan, two Su-25 jets took off on Armenian territory and later crashed into a mountain. At around 22:00, the Armenian MoD stated an Azerbaijani ammunition convoy had been destroyed. Approximately one hour later, the Azerbaijani MoD stated its forces had destroyed an Armenian position near Həsənqaya in Tartar District and another in the direction of Talış.

30 September According to the Armenian MoD, the clashes continued with lesser intensity overnight. At approximately 08:30, the Azerbaijani MoD stated that Armenian forces had been shelling Tartar City. At approximately 10:20, the Azerbaijani MoD stated that its units had surrounded Armenian forces with the aid of artillery fire, and that clashes continued in the Aghdara/Martakert–Tartar area of the front. At approximately 10:20, the Ministry stated that Armenian forces had started firing upon Aşağı Ağcakənd, in Goranboy District. At approximately 11:10, the Armenian MoD stated that the Azerbaijani Air Force was attacking Armenian positions in the northern direction of the front.

At approximately 12:25, the Azerbaijani MoD stated that the Armenian 7th Mountain Rifle Regiment of the 10th Mountain Rifle Division, stationed in Tonaşen, had incurred heavy losses and retreated; it released footage apparently showing the attack and stated that Azerbaijani forces attacked the command post of tan Armenian regiment of the 18th Motorized Division, inflicting casualties. The Armenian MoD stated that Armenian forces had destroyed a substantial quantity of Azerbaijani materiel, including a TOS-1A. The Ministry also stated that Azerbaijani forces had shelled the 4th Armenian Battalion, stationed in Fuzuli District, and that its forces had attacked the headquarters of an Armenian regiment of the 10th Mountain Rifle Division, stationed in Aghdara. The Armenian MoD stated that Armenian forces had destroyed Azerbaijani outposts and materiel.

October 1 October According to the Azerbaijani MoD, clashes continued overnight, with Azerbaijani units shelling Armenian positions, while the ADA stated that the overnight situation had been relatively stable. At approximately 10:00, the Azerbaijani MoD stated that Armenian forces had been shelling Tartar City during the morning. The Armenian MoD stated that Armenian forces shot down an Azerbaijani UAV near Askeran, while the Artsakh MoD stated that Artsakh forces had repelled Azerbaijani advances. About half an hour later, it stated that Artsakh forces had downed an Azerbaijani gunship near Lalatapa, with wreckage falling into Iranian territory; Azerbaijan issued a denial.