Fierce conflict in the fury of over a century in the ethnic Armenian enclave of Azerbaijan.
Al Jazeera also learned on Tuesday that the total number of civilians killed has increased from 11 – nine in Azerbaijan and two in Armenia, bringing the total death toll to 95.
“This is a life and death war,” the Nagorno-Karabakh leader, Aryik Harututian, said in a news briefing by the Reuters news agency.
Officials in Baku and Yerevan said fierce clashes continued throughout the day on Monday.
Armenia’s Ministry of Defense spokesman Artrun Hovhannisen said on Monday evening, Azerbaijan’s forces “launched a massive offensive in the southern and northeastern regions of the Karabakh border line.”
The Karabakh Defense Ministry said in a statement on Monday, “Twenty-six soldiers of Qarabakh’s defense army were killed.”
World leaders have urged a halt to the fighting after the worst escalation since 2016, raising the specter of another war between former Soviet rivals Armenia and Azerbaijan.
The United Nations Security Council will hold emergency talks behind closed doors on Tuesday, following a push by France and Germany to put the issue on the agenda.
Decades old controversy
Armenia and Azerbaijan were locked in a territorial dispute since the 1990s, when Karabakh, an ethnic Armenian enclave within Azerbaijan, declared independence after a war that killed about 30,000 people.
The independence of Nagorno-Karbakh is not recognized by any country, and is considered part of Azerbaijan by the international community.
Azerbaijan has not released information on military casualties since the latest fighting began.
The fight between Azerbaijan and Armenia could destabilize the wider region and embassy countries, including Russia and Turkey.
Russia, which has a military alliance with Armenia, sells sophisticated weapons worth billions of dollars to both Baku and Yerevan.
Armenia has accused Turkey – which supports Ottoman-speaking Azerbaijan – of mediating the conflict.
Greater risk of civilian casualties
Armenian Foreign Ministry spokesman Anna Nagdalayan said Turkish military experts were fighting with Azerbaijan and Turkey provided drones and war planes.
Azerbaijan denied the allegations, while Turkey has called for an end to the fighting.
Negotiations to resolve one of the worst conflicts to emerge from the fall of 1991 of the Soviet Union came to a close in 1994 when a cease-fire was agreed.
France, Russia and the United States have mediated peace efforts under the Minsk group’s umbrella, but the last major push for a peace deal collapsed in 2010.
“We have not seen anything like this since the ceasefire in the 1990s. The fight is happening with all sections of the front line, ”Olesa Vartanyan, senior analyst for the South Caucasus region at the International Crisis Group, told Reuters.
Wartian said the use of rockets and artillery increased the risk of civilian casualties that could make the escalation harder to deter diplomatic means.
Russia immediately called for a ceasefire and Turkey said that it would support Azerbaijan.
Turkish President Recep Tayyip Erdogan has demanded that Armenia immediately leave the land of Azerbaijan, adding that it was occupying and said that it was time to end the Nagorno-Karabakh crisis.