Azerbaijan uses internationally banned chemical weapons (phosphorus) against Artsakh inflicting mass environmental​ destruction.

Meeting of the Foreign Minister of Armenia and Azerbaijan was held in Geneva with the participation of the OSCE Minsk Group Co-Chairs, as well as with Personal Representative of the OSCE Chairperson-in-Office Andrzej Kasprzyk.

A US-mediated humanitarian ceasefire agreement was reached and was violated by Azerbaijan minutes after entry it entered into force.

After 21 days of fighting, President of Azerbaijan Ilham Aliyev and Prime Minister of Armenia Nikol Pashinyan agree to meet.

A second ceasefire is agreed upon but only holds for a few minutes before the fighting resumes as Azerbaijan announces that the ceasefire is only for purposes of recovering dead and wounded soldiers from the area and is not intended to halt combat operations.

After a meeting in Moscow with the foreign ministers of Russia, Armenia, and Azerbaijan, a humanitarian ceasefire is agreed upon to be observed starting at noon on October 10 but gets quickly violated due to renewed Azerbaijani shelling.

Azerbaijan initiates a full-scale offensive along the entire line of contact between Armenian and Azerbaijani forces in Karabakh, dubbing it as a “counter-attack” against an Armenian offensive.

Turkey pledges full support to Azerbaijan’s efforts to restore its territorial integrity. Joint military exercises take place in Nakhichevan and Baku for which Turkey transports F-16 fighter jets and other military equipment to Azerbaijan.

Tensions rise as Azerbaijani forces attempt to cross over to the Armenian side in Tavush triggering a direct hit that leaves 4 Azerbaijani officers dead. A wave of pro-war protests starts in Azerbaijan. The escalation leaves behind 18 combined dead and is the deadliest since 2016.

The situation gets tense on the border as Azerbaijan carries missile strikes against Armenian defensive positions.

Azerbaijan initiates the largest offensive since the conclusion of active fighting in 1994. During the course of 4 days, heavy artillery and drones are involved in fighting along with the armies as both sides suffer hundreds of casualties. Azerbaijan claims control over certain strategic hilltops in the southern section of the line of contact.

After a meeting in Washington between Aliyev and US Secretary of State John Kerry, the Azerbaijani president declares a solution is only possible if Armenian forces withdraw from Karabakh. Hours later Azerbaijan begins the offensive.

The Presidents of the Republic of Armenia and the Republic of Azerbaijan express readiness to expedite the process of reaching understanding with regard to the Basic Principles, taking into account all the work conducted so far.

Аfter a series of preparatory meetings, the Presidents of Russia, Azerbaijan and Armenia stated at a meeting in Kazan that "a mutual understanding has been reached on a number of issues." It later became known that Aliyev had stated during the same meeting that he would not give his consent to the Kazan document.

Attempting to use the instability in Armenia following the disputed presidential elections and subsequent violence in Yerevan on March 1, Azerbaijan escalates the situation in Martakert, Karabakh, leading to several casualties.

After a meeting in Madrid, the OSCE Minsk Group Co-chairs announce that a set of Basic Principles for the peaceful settlement of the conflict is proposed.

During NATO training in Budapest, Azerbaijani officer Ramil Safarov murders Armenian officer Gurgen Margaryan with an ax in his sleep, triggering international condemnation and deepening mistrust between Armenian and Azerbaijani societies.

The OSCE Minsk Groups establishes the trilateral Co-chairmanship format of the United States, France, and Russia, still in effect until today.

OSCE established the co-chairmanship of the Conference on Nagorno Karabakh under the auspices of the OSCE Minsk Group.

A protocol signed in Kyrgyzstan’s capital Bishkek by Armenia, Azerbaijan, and Nagorno Karabakh, and brokered by Russia, establishes the ceasefire effectively ending the 4-year-long war in Karabakh.

Armenian forces establish control over Jebrayil, Kubatli districts, and part of Fizuli, surrounding Karabakh.

Armenian forces take control of Lachin, establishing a corridor between Armenia and Karabakh.

Armenians take Shushi, effectively ending the siege and bombardment of Stepanakert from the GRAD launchers located in Shushi.

Azerbaijani forces enter the village of Maragha, murdering some forty civilians.

The Siege of Stepanakert begins with shelling by missiles launched from Agdam.

Armenia declares independence after the positive results of the nationwide referendum.

Nagorno Karabakh declares itself a republic.

Supported by Soviet internal troops, Azerbaijani SWAT units initiate Operation Ring, under the guise of passport control, uprooting and deporting the populations from villages in Karabakh.

Pogroms of the Armenian population in Baku lead to their exodus and numerous deaths.

Legislatures of Soviet Armenia and Nagorno Karabakh Autonomous Oblast make declarations of unification.

The Supreme Council of the USSR rejects the Armenian demands of unification.

Nagorno Karabakh Autonomous Oblast regional legislature votes in favor of unification with Soviet Armenia.

Soviet Azerbaijan expresses opposition to calls of transferring Nagorno Karabakh Autonomous Oblast to Soviet Armenia.

Soviet Armenian legislature votes in favor of unifying with Nagorno Karabakh Autonomous Oblast.

Nagorno Karabakh Autonomous Oblast legislature passes a resolution asking for unification with Armenia.

Soviet leader Gorbachev rejects Armenian calls of unification.

Pogroms in the Azerbaijani city of Sumgait lead to the deaths of dozens of Armenians at the hands of Azerbaijani mob and the exodus of the large Armenian community.

First clash in the town of Askeran in Karabakh.

NKAO legislature issues a request to join with Soviet Armenia.

Massive demonstrations in Yerevan in support of unification with Karabakh.

The first major demonstration in Stepanakert signals the beginning of the Karabakh Movement.

Soviet Azerbaijan establishes the Nagorno Karabakh Autonomous Oblast (region).

By the revised decision of the Caucasus Bureau, Karabakh with its Armenian majority was placed under Soviet Azerbaijani control instead of Soviet Armenian, citing economic ties.

The meeting of the Caucasus Bureau reaffirmed Karabakh as part of Soviet Armenia.

After Armenia became Sovietized, Azerbaijan issued a statement recognizing the disputed territories of Nakhijevan, Zangezur, and Karabakh as parts of Soviet Armenia.

Republics of Armenia and Azerbaijan became independent following the Russian Revolution. Azerbaijan tried to control Karabakh but was not successful due to resistance from the local Armenian population.