Armed forces from both countries clash after Azerbaijan launches a military operation in the region.
Armenia said neighboring Azerbaijan has attacked civilian settlements in the disputed Nagorno-Karabakh region and its residents seeking shelter in shelters as the worst clashes since 2016 raise the specter of another major war.
The arch enemies Azerbaijan and Armenia have been embroiled in a territorial dispute over the mainly ethnic-Armenian region for decades.
The Armenian Defense Ministry said on Sunday that its troops shot down two Azerbaijani helicopters and three drones in response to an attack that began at 04:10 GMT against civil settlements, including the regional capital, Stepanakert.
“Our response will be proportionate and the Azerbaijani military leadership bears full responsibility for the situation,” the ministry said in a statement.
The Azerbaijani Defense Ministry said it had launched a military operation along the “Contact Line,” a heavily mined no man’s land that separates Armenian-backed forces from Azerbaijani troops in the region, Russian news agencies reported.
The ministry said an Azerbaijani helicopter was shot down, but its crew survived.
The Armenian Foreign Ministry condemned the so-called “aggression of the Azerbaijani military-political leadership” and said the Armenian side would provide an appropriate military and political response.
“Let us stand firmly behind our state, our army … and we will win. Long live the glorious Armenian army! “Armenian Prime Minister Nikol Pashinyan wrote on Facebook.
Ethnic Armenians in Nagorno-Karabakh declared their independence during a conflict that collapsed in 1991 when the Soviet Union collapsed. They seized Karabakh of Baku in a war in which 30,000 people were killed.
Although a ceasefire was agreed in 1994, Azerbaijan and Armenia frequently accuse each other of attacks around Nagorno-Karabakh and along the border between Azerbaijan and Armenia.
Talks to settle the Nagorno-Karabakh dispute have largely stalled since the ceasefire agreement.
The Minsk Group, which includes France, Russia, and the United States, has worked to mediate the dispute, but the last major push for a peace deal collapsed in 2010.
Energy-rich Azerbaijan has invested heavily in its military and has repeatedly vowed to retake Karabakh by force. Armenia has announced that it will defend the territory that has declared independence but relies heavily on Yerevan.