YEREVAN, Armenia (AP) — A drone strike by Azerbaijan on Friday killed three Nagorno-Karabakh soldiers, the territory’s defense ministry said.

The incident raised concerns about the stability of a 2020 ceasefire that ended the Azerbaijani-Armenian war over Nagorno-Karabakh. More than 5,500 soldiers lost their lives in the six-week war, which ended with Azerbaijan’s recapture of areas around Nagorno-Karabakh that had been under Armenian control since the end of a separatist war in 1994.

Most of this territory remains under the control of ethnic Armenian forces, although it is within Azerbaijan. Russia mediated the ceasefire, then sent some 2,000 troops it called peacekeepers to the region.

The ministry did not give details of the attack. Gegam Stepanian, the Nagorno-Karabakh ombudsman, said 14 other people were injured.

An ethnic Armenian soldier walks with the Nagorno-Karabakh flag on Wednesday, November 25, 2020, towards a checkpoint near the town of Charektar, in the separatist Nagorno-Karabakh region, on a new border with the Kalbajar district handed over to Azerbaijan. . (AP Photo/Sergei Grits)