Azerbaijan launched "anti-terrorist activities" in the Nagorno-Karabakh region on Tuesday (Sep 19), saying it wanted to restore constitutional order and drive out what it said were Armenian troops, a move that could foreshadow a new war.

Armenia and Azerbaijan have already fought two wars over Karabakh in the three decades since the Soviet Union they were both members of collapsed.

Here is a look at the history of the conflict and the latest developments.

WHAT IS NAGORNO-KARABAKH?

Nagorno-Karabakh, known as Artsakh by Armenians, is a mountainous region at the southern end of the Karabakh mountain range, within Azerbaijan.

It is internationally recognised as part of Azerbaijan, but its 120,000 inhabitants are predominantly ethnic Armenians. They have their own government which is close to Armenia but not officially recognised by Armenia or any other country.

Armenians, who are Christian, claim a long presence in the area, dating back to several centuries before Christ. Azerbaijan, whose inhabitants are mostly Turkic Muslims, also claims deep historical ties to the region, which over the centuries has come under the sway of Persians, Turks and Russians. Bloody conflict between the two peoples goes back more than a century.

Under the Soviet Union, Nagorno-Karabakh became an autonomous region within the republic of Azerbaijan.

FIRST KARABAKH WAR

As the Soviet Union crumbled, the First Karabakh War (1988 to 1994) erupted between Armenians and their Azeri neighbours. About 30,000 people were killed and more than a million displaced. Most of those were Azeris driven from their homes when the Armenian side ended up in control of Nagorno-Karabakh itself and swathes of seven surrounding districts.

44-DAY WAR IN 2020

In 2020, after decades of intermittent skirmishes, Azerbaijan began a military operation that became the Second Karabakh War, swiftly breaking through Armenian defences. It won a resounding victory in 44 days, taking back the seven districts and about a third of Nagorno-Karabakh itself.

The use of drones bought from Turkey and Israel was cited by military analysts as o...