AZERBAIJAN looked set on Wednesday to regain control of the breakaway ethnic Armenian-populated region of Nagorno-Karabakh after a 24-hour offensive, having fought two wars with Armenia over the territory in the past 30 years.

Here is a quick guide to what's going on.

WHAT IS NAGORNO-KARABAKH?

Nagorno-Karabakh, known as Artsakh by Armenians, is a mountainous region within Azerbaijan that is internationally recognised as part of that country. But its 120,000 inhabitants are predominantly ethnic Armenians who broke away during a first war in the 1990s after the collapse of the Soviet Union.

In a 44-day war in 2020, Azerbaijan recaptured seven surrounding districts and took back about a third of Nagorno-Karabakh itself.

WHAT IS AZERBAIJAN TRYING TO ACHIEVE?

Hikmet Hajiyev, foreign policy adviser to President Ilham Aliyev, told Reuters on Tuesday that Azerbaijan wanted to establish full sovereignty over its territory and would not talk to Karabakh's Armenians unless they surrendered and disarmed.

WHY NOW?

Azerbaijan has been tightening pressure on Nagorno-Karabakh for months, effectively blocking its lifeline road connection with Armenia - the "Lachin corridor". That caused acute shortages of food and medicines.

A force of 2,000 Russian peacekeepers did little to keep the road open, reinforcing the impression that Moscow was too preoccupied with war in Ukraine to deal with crises elsewhere. The Karabakh Armenians declined, until last week, to open a road link to the Azerbaijani city of Aghdam.

Russia's relations with Armenia, whose support the Karabakh Armenians have relied on for three decades, have deteriorated sharply, reducing the likelihood that Moscow would come to their aid. Armenia has no other powerful ally it can count on, while Azerbaijan is backed by neighbouring Turkey.

WHY DOES IT MATTER?

Conflict in the region between between Christian Armenians and Turkic Muslim Azeris goes back more than a century.

About 30,000 people were killed and more than a million displaced in the war in the 1990s, and at least 6,500 died in the 44-day war in 2020.

The latest conflict could shift the balance of power in the wider region, where Russia, Turkey, Iran and the West all have competing interests.

Russia sees itself as the security guarantor in the South Caucasus, but its influence is eroding. Azerbaijan said it had given Moscow only minutes' notice of Tuesday's offensive, despite Russia's peacekeeping role and frequent calls for restraint.

WHAT HAPPENS NEXT?

The two sides said they had agreed to a ceasefire proposed by Russian peacekeepers under which the Karabakh forces would disband and disarm, and that talks on the future of the region and the ethnic Armenians who live there would start on Thursday, Sept. 21.

Such a deal would put Azerbaijan close to achieving all its objectives, while any further fighting could increase the risk of a bigger war between Azerbaijan and Armenia.

Even in normal times, clashes along their shared border are not infrequent, and tensions are now running very high.

HOW STRONG ARE THE RESPECTIVE ARMIES?

Azerbaijan has total armed forces of 64,000 and available reserves of 300,000 according to the International Institute for Strategic Studies. Karabakh's separatist forces are estimated to number only about 5,000.

Armenia has total armed forces of around 43,000 and an estimated 210,000 reserves. It is weaker than Azerbaijan, especially in terms of air power, and its 2022 defence budget of $750 million was less than a third of Azerbaijan's $2.6 billion.

WHAT IS THE OUTSIDE WORLD SAYING?

Turkey, Azerbaijan's ally, said it supported what it called Baku's steps to preserve its territorial integrity.

Russia, which has a defence treaty with Armenia, noted pointedly that Baku had been taking action on its own sovereign territory. It said its peacekeepers would help to implement the Sept. 20 ceasefire.

The United States, the EU and Russia had all tried for years to nudge Nagorno-Karabakh's backer Armenia towards a permanent peace deal with Azerbaijan. But the attempts all foundered over Armenia's demand that Azerbaijan should agree to protect the rights and security of Karabakh's ethnic Armenians - something Baku said was unnecessary and amounted to interference in its internal affairs.

Their appeals on Tuesday for Baku to halt its offensive went unheeded.