Azerbaijan's Defense Ministry has said that one of its soldiers was killed in a late-morning incident near the border with arch-foe Armenia.
It called the death of the junior sergeant in the Tovuz region of northwestern Azerbaijan the latest "provocation" amid a rise in violations.
Last week, Armenian officials announced that one of their soldiers was killed by gunfire and shrapnel in roughly the same region.
Each side has blamed the other for an uptick in violations of a decades-old cease-fire, and contradictory reports make determining responsibility difficult.
Yerevan and Baku are still technically at war over Azerbaijan’s breakaway region of Nagorno-Karabakh despite a 1994 cease-fire in a conflict that killed around 30,000 people.
Skirmishes frequently break out near the so-called Line of Contact that separates Armenian and Azerbaijani forces on the front line of Europe's longest-running conflict.
Fighting along the two sides' internationally recognized state border is slightly less common.
A days-long flareup that included drone attacks and heavy artillery fire in mid-July killed at least 17 people, mostly soldiers on both sides but including at least one civilian, in the worst fighting in about four years.
Azerbaijani President Ilham Aliyev recently challenged Moscow over what Baku alleged was an increased flow of weapons to Armenia since the July fighting.
Russia, which has a military base in Armenia, regards Yerevan as a strategic partner in the region.
Aliyev has meanwhile downplayed the prospects for stalled internationally mediated talks on finally ending the Nagorno-Karabakh conflict.
"Talks are not being conducted in fact," he said on September 20, adding, "I've said that we won't participate in talks for the sake of imitation."
Azerbaijan claimed on September 20 to have downed an Armenian drone.
With reporting by Reuters and Asbarez