Armenia said that its military shot down drones belonging to Azerbaijani forces with one reaching within 10 miles of Yerevan, although Baku denies this.

“Armenian air defense forces have already eliminated three [drones],” the Armenian government tweeted on Thursday, as the dispute over the predominantly Armenian-populated region threatens to draw in Turkey and Russia.

Meanwhile, the defense ministry of Nagorno-Karabakh said that the death toll in the biggest eruption in the decades-long conflict had reached 154, after another 54 casualties on Friday.

Olesya Vartanyan from the International Crisis Group said that artillery, rockets, and drones have struck populated areas close to the frontline and deeper inside the Nagorno-Karabakh conflict region.

She said people in the territory’s capital, Stepanakert, have taken refuge in basements and shelters and with hundreds of thousands of people living close to the frontline, there is the real risk of mass casualties.

Azerbaijan forces claimed to have made advances, but accused Armenia of artillery attacks on four villages, causing civilian casualties. Baku said at least 19 civilians have been killed in Armenian shelling.

Central to any resolution at the table of diplomacy is the OSCE Minsk Group, set up to negotiate between the South Caucasus neighbors. Armenia’s foreign ministry threw its weight behind its role in talks.

“While this aggression against Nagorno-Karabakh will continue to receive our strong and resolute response, we stand ready to engage with the OSCE Minsk Group Co-Chair countries to re-establish a ceasefire regime based on the 1994-1995 agreements,” the Armenian foreign ministry said in a statement, referring to the deal negotiated by Russia following the last conflict over the territory. That conflict killed at least 30,000 people and displaced many more.

With Turkey firmly backing Azerbaijan in the latest spike in tensions, what Ankara does next will be key. Armenian officials claimed Ankara is sending troops from Syria to the region and deploying Turkish F-16 fighter jets, which Turkey has denied. Turkish President Recep Tayyip Erdoğan said on Friday: “This struggle will continue until Nagorno-Karabakh is freed from the occupation.”

Azeri President Ilham Aliyev said: “Azerbaijan said only the Armenians’ withdrawal from the region can guarantee a ceasefire.”

The European Council called for an immediate end to hostilities, saying in a statement on Friday that “the loss of life and the toll on the civilian population are unacceptable.

“There can be no military solution to the conflict, nor any external interference. Azerbaijan and Armenia should engage in substantive negotiations without preconditions,” it added.

Zaur Shiriyev, South Caucasus analyst for the International Crisis Group, said that neither Baku nor Yerevan are likely to back off. “For that to happen, we would need to see more proactive international diplomacy with the aim of returning to the negotiation table. This is extremely difficult to do,” he told Newsweek.