Azerbaijani armed forces started shelling Armenian positions in Karabakh, which local Armenians call Artsakh, around 1pm on September 19 as it appears the war between the long-time enemies has broken out again.

According to the Ministry of Defence, Azerbaijan has launched what it is calling an “anti-terrorist operation” in the Karabakh region in response to systematic shelling of its positions by Armenian forces.

A spokesman for Azerbaijan told local television that Azerbaijan was targeting Armenian troops and military positions but that the civilian population were “out of the game” and would not be targeted or hurt.

However, air raid sirens and mortar fire were heard in Karabakh's main city, Khankendi, known as Stepanakert by Armenians and home to a large share of the local population. Defence officials in the breakaway region said the Azerbaijani military had "violated the ceasefire along the entire line of contact with missile-artillery strikes", the BBC reported. Armenia's defence ministry said that claims of Armenian military fire did not correspond with reality.

A video from Stepanakert appeared to show bomb raid warnings blaring and the audible sounds of artillery fire. Other videos from the region seemed to show Azerbaijan using drones to strike Armenian anti-air defence positions, the Guardian reported.

The Azerbaijani ministry said that Armenia has also been mining Azerbaijani territories, enhancing engineering support for its battle positions, and increasing the number of trenches and shelters in the region. In addition, Armenia has been fortifying its battle positions with military personnel, armoured vehicles, artillery gun mounts, and other firepower, bringing units to a high level of combat readiness, and creating additional mobilisation units. These claims could not be verified.

On September 19, two civilians and seven policemen were killed and several other military personnel were injured when their vehicles hit landmines planted by Armenian forces on the Ahmadbayli-Fuzuli-Shusha Road, it was claimed.

The Azerbaijani defence ministry said that the anti-terrorist operation is aimed at suppressing large-scale provocations in the Karabakh economic region, disarming and securing the withdrawal of Armenian forces from Azerbaijani territories, neutralising Armenian military infrastructure, and providing safety for the civilian population and military personnel.

The ministry said that it is using high-precision weapons to incapacitate positions on the front line and in-depth, long-term firing points of Armenian forces, as well as combat assets and military facilities. It also said that the civilian population and civilian infrastructure facilities are not being targeted. An estimated 120,000 ethnic Armenians live in the mountainous enclave.

The command of the peacekeeping contingent of the Russian Federation and the leadership of the Turkish-Russian Monitoring Centre have been informed of the ongoing activities.

Armenian President Nikol Pashinyan has been complaining for months that the Azerbaijani forces have been blocking the Lachin corridor, the only route in and out of Karabakh that is largely populated by ethnic Armenians and was causing a humanitarian crisis. Large parts of Stepanakert have been cut off from water or electricity for several months.

However, after months of denying access to the enclave, Azerbaijani forces allowed the passage of some humanitarian aid to the enclave on September 18.

Russia, which is supposed to be the guarantor of a tripartite peace deal brokered two years ago, has been largely passive in the growing conflict and has not acted to end what could also be seen as breakdown of the ceasefire agreement.

Russia's foreign ministry said it had been warned of the Azerbaijani offensive only minutes in advance and urged both countries to respect a ceasefire signed after the war in 2020, the BBC reported. The EU's regional special representative, Toivo Klaar, said there was "urgent need for immediate ceasefire".

The anti-terrorist operation comes amid heightened tensions in the region. In recent months, there have been several clashes between Azerbaijani and Armenian forces. In September 2022, Azerbaijan launched an operation called "Revenge" against Armenian forces after Armenia opened fire and killed an Azerbaijani soldier.

The Nagorno-Karabakh conflict is a long-running dispute over the control of the Nagorno-Karabakh region, which is internationally recognized as part of Azerbaijan but is populated by ethnic Armenians. The conflict has been the source of several wars and clashes between Azerbaijan and Armenia.

In 2020, Azerbaijan and Armenia signed a trilateral ceasefire agreement that ended a 44-day war over Nagorno-Karabakh. The agreement also provided for the deployment of a Russian peacekeeping contingent to the region. However, the ceasefire has been fragile, and there have been several violations in recent months. The Azerbaijani government has accused Armenia of violating the terms of the agreement by maintaining an illegal military presence in Nagorno-Karabakh and by mining Azerbaijani territories.