YEREVAN, Armenia (AP) — Armenia and Azerbaijan on Thursday traded blame for border clashes in which officials say at least one soldier was killed and two others were wounded amid simmering tensions between the ex-Soviet neighbors.

Armenia’s military said that two of its troops were wounded after Azerbaijani forces opened fire on Armenian positions, while Azerbaijan said Armenian forces killed one of its soldiers in what it called “a provocation.”

Armenia and Azerbaijan have been locked in a decades-old dispute over the separatist region of Nagorno-Karabakh, which lies within Azerbaijan but was under the control of ethnic Armenian forces backed by Armenia since a separatist war there ended in 1994.

Moscow brokered a peace deal last November to end six weeks of fighting over the territory, during which more than 6,600 people were killed. The Russia-brokered truce allowed Azerbaijan to reclaim control over large parts of Nagorno-Karabakh and surrounding areas that the Armenia-backed separatists controlled.

Tensions on the two nations’ border have been building since May, when Armenia protested what it described as an incursion by Azerbaijani troops into its territory. Azerbaijan has insisted that its soldiers were deployed to what it considers its territory in areas where the border has yet to be demarcated. Clashes have been reported ever since.

Last month, Russian President Vladimir Putin hosted leaders of Armenia and Azerbaijan for talks in Sochi. After the meeting, Putin said that the three leaders agreed to create, before the end of the year, mechanisms for delimitation and demarcation of the border between the two countries.