Azerbaijan announced a "revenge operation" in response to cross-border fire by Armenia on Monday, while Armenia reported its four soldiers were killed in the operation and Russia urged restraint.
"As a result of the operation, the combat post of the Armenian Armed Forces near the Nerkin-And settlement of Gafan district, where our soldiers were fired upon yesterday (Monday), was completely destroyed, and the combat positions were silenced," a statement by Azerbaijan's State Border Service said Tuesday.
Azerbaijan earlier announced that a serviceman was injured by Armenian fire on Monday.
There are reports of serious casualties among the personnel of the destroyed combat post, the statement noted, saying: "Every provocation of the Armenian side aimed at aggravating the operational conditions at the Azerbaijan-Armenia conditional state border will be answered with more serious and decisive measures from now on."
"The military and political leadership of Armenia is fully responsible for the incident," it added.
Earlier, the Azerbaijani Defense Ministry also said its military positions in the country's northwestern Tovuz district were fired on by Armenia late Monday.
Relations between Azerbaijan and Armenia have been tense since 1991, when the Armenian military occupied Nagorno-Karabakh, a territory internationally recognized as part of Azerbaijan, and seven adjacent regions.
Azerbaijan liberated most of the region during the war in the fall of 2020, which ended with a Russian-brokered peace agreement, opening the door to normalization. The Azerbaijani army initiated a counterterrorism operation in Karabakh last September to establish constitutional order after which illegal separatist forces in the region surrendered.
Armenia's Defense Ministry said in a statement posted on the Telegram messaging app on Tuesday that two of its soldiers had been killed and several more wounded at a combat post near the southern Armenian village of Nerkin Hand.
Although fatal exchanges of fire between Armenia and Azerbaijan have been common for decades, the border has become more peaceful since the start of peace talks, with little serious fighting since the collapse of Karabakh in September 2023.
The peace talks have stagnated in recent months, with both sides accusing the other of sabotaging the diplomatic process.
Armenian Prime Minister Nikol Pashinyan proposed last month to Azerbaijan to sign a non-aggression pact, pending a comprehensive peace treaty between the neighbors.
Pashinyan and his Azerbaijani counterpart Ilham Aliyev had previously said a peace agreement could have been signed by the end of last year.
Moscow urges 'restraint'
Russia – which used to be the main mediator of the conflict but has in recent years been bogged down by its Ukraine invasion – urged calm and called the violence "worrying."
"We call on both sides to show restraint to avoid any acts that the opposite side could see as provocative," Kremlin spokesperson Dmitry Peskov said Tuesday.
Armenia has distanced itself from its historic ally Russia since Azerbaijan's offensive, with Yerevan angry that Moscow's peacekeeping force in Karabakh did not act during Azerbaijan's recapture.
Baku has denied having territorial claims to Armenia after having regained Karabakh and ruled out a fresh conflict with Yerevan.