Dozens of soldiers have been killed in fighting between neighbouring countries Armenia and Azerbaijan.
Armenia’s Prime Minister Nikol Pashinyan said 49 of its soldiers died in overnight clashes.
The two countries have fought two wars and seen regular smaller clashes over the course of three decades.
Russia claimed it had brokered a ceasefire for the latest outbreak – but Armenia said only that the fighting had calmed, rather then ended completely.
At the core of the dispute is the region of Nagorno-Karabakh. It is, according to internationally-recognised borders, firmly a part of Azerbaijan – but is populated by ethnic Armenians.
The cultural divide extends beyond politics into religion, too: Armenia is a majority-Christian country, while Azerbaijan is mostly Muslim.
The dispute has led to full-scale war in the 1980s and 1990s, a six-week war in 2020, and continuing clashes for decades.
Both countries blame the other for the latest outbreak of violence.
Armenia claimed that several towns along the border had been shelled by its neighbour, and that it had responded to the provocation. Azerbaijan said its military positions came under attack first.
Violence continued on Monday night before Moscow said it had negotiated a rapid ceasefire to take effect early Tuesday morning.
Armenia’s Nikol Pashinyan, however, said “the intensity of hostilities has decreased but attacks on one or two fronts from Azerbaijan continue.”
Azerbaijan is understood to have also suffered casualties, but has not publicly issued a statement on the number of injured or dead.
The fighting has been condemned internationally, with US Secretary of State Antony Blinken saying, “there can be no military solution to the conflict”.
Russia, which is historically close to Armenia, said the ongoing dispute “should be resolved exclusively through political and diplomatic means”.
It urged both sides to “exercise restraint”.
Turkey has ties with Azerbaijan, and seemingly backed its version of events. Turkey’s foreign minister Mevlut Cavusoglu, said “Armenia should cease its provocations and focus on peace negotiations”.
Monday night’s fighting is believed to be the worst since the 2020 conflict, in which thousands were killed. That war ended in a deal brokered by Russia, which saw Armenia withdraw its troops from occupied areas around Nagorno-Karabakh.
A Russian peacekeeping force of nearly 2,000 mean was deployed to the area as part of the negotiations.