Azerbaijan and Armenia have blamed each other for the failure of a third attempt to implement a ceasefire over the contested region of Nagorno-Karabakh, which Baku says it is determined to reclaim through military force or diplomacy.
The neighbouring south Caucasus states agreed to a truce during weekend talks in Washington, but within minutes of its supposed start on Monday morning they accused each other of breaking the deal – just as they did after earlier ceasefire efforts brokered by Russia and France.
Hundreds of soldiers and scores of civilians have been killed since fierce fighting resumed in late September over Nagorno-Karabakh, a breakaway region of Azerbaijan that has been run by its ethnic Armenian majority since a war in the 1990s.
Azerbaijan's main ally Turkey has backed its drive to retake the mountainous province, raising tension between Ankara and Russia, which has a security treaty with Armenia and maintains a military base there. Turkey and Russia back opposing sides in conflicts in Syria and Libya, and are jostling for influence across a wide area.
In an address to his nation on Monday, Azeri president Ilham Aliyev said the country's military had retaken more territory in and around Nagorno-Karabakh and was "restoring historical justice on the battlefield".
“My people know my position: this question should be resolved by military or peaceful means,” he said, adding that if Armenia wanted a political solution, it should present a timetable for the withdrawal of its forces from Nagorno-Karabakh.
Energy-rich Azerbaijan says three decades of diplomacy over the conflict by the so-called Minsk group – chaired by Russia, the United States and France – have failed and Turkey must now play a major role in resolving the dispute.
“We are sick to the back teeth of these talks. How long can you negotiate with the enemy?” Mr Aliyev said. “Everything the Minsk group does is aimed at saving Armenia.”
Turkey rejects allegations that it has sent fighters from Syria to bolster Baku’s forces, but Mr Aliyev acknowledged that several Turkish F-16 jet fighters had remained at an Azeri airfield after joint military exercises in July.
“Our Turkish brothers left them here as moral support for us. But if there should be any foreign aggression towards us, then [the aggressor] will see these F-16s,” he said.
Armenian prime minister Nikol Pashinyan said his country was "ready to make mutual concessions, even concessions that are painful for us, but the Armenian people will never be ready to surrender."
Without naming Turkey, Russia has urged all states in the region to refrain from bellicose rhetoric, and Moscow insists it will meet its treaty obligation to defend Armenia if its territory is attacked.
Moscow-Ankara relations could be further strained by reported Russian bombing on Monday of a training camp for Turkish-backed fighters in Syria, which killed dozens of people.