Baku and Yerevan put themselves on a war footing after heavy fighting erupted yesterday between Azerbaijan and Armenian separatists, claiming military and civilian casualties on both sides, including at least one child.
The worst clashes since 2016 have raised the specter of a fresh large-scale war between arch-enemies Azerbaijan and Armenia that have been locked for decades in a territorial dispute over the Armenia-backed breakaway region of Nagorny Karabakh.
A major confrontation between the ex-Soviet Caucasus neighbors would draw in big regional players Russia and Turkey.
Russia, France, Germany and the European Union swiftly urged an "immediate ceasefire," while Pope Francis prayed for peace.
Azerbaijan's ally Turkey blamed Yerevan for the flare-up and promised Baku its full support.
Azerbaijan said it had captured seven of its Armenian-controlled villages, a claim Yerevan denied.
In a televised address to the nation, Azerbaijan President Ilham Aliyev vowed victory over Armenian forces. "Our cause is just and we will win," Aliyev said, repeating a famous quote from Joseph Stalin's address at the outbreak of World War II in Russia.
"Get ready to defend our sacred homeland," Armenian Prime Minister Nikol Pashinyan said on Facebook.
Armenia said earlier yesterday that Azerbaijan attacked civilian settlements in Nagorny Karabakh including the main city Stepanakert.
Azerbaijan accused Armenian forces of violating a ceasefire, saying it had launched a counter-offensive to "ensure the safety of the population," using tanks, artillery missiles, combat aviation and drones.
Armenian separatists seized the Nagorny Karabakh region from Baku in a 1990s war that claimed 30,000 lives.