Tensions in the South Caucasus region are rising again as Armenian armed forces opened fire on Azerbaijani army positions for the fourth time in the past week.

The Azerbaijani Defense Ministry on Monday said Armenian forces opened fire on Azerbaijani military posts in the Kalbajar district in East Zangezur overnight.

"On Aug. 18, at about 23:50, the Armenian armed forces stationed in the direction of Zarkand settlement in the Basarkechar region using small arms subjected to fire on the Azerbaijan Army positions stationed in the direction of the Damirchidam settlement of the Kalbajar region," it said.

The Azerbaijani military "took adequate retaliatory measures in the mentioned direction," it added.

The incident occurred while Russian President Vladimir Putin was in Baku, where he intended to discuss, among other things, the Armenian-Azerbaijani settlement with Azerbaijan's top officials.

It was also the fourth time Armenian forces shelled border positions of the Azerbaijani army in the past week.

Last Thursday, Baku said Armenian forces fired on military positions near the settlement of Ganza, about 5 kilometers (3.1 miles) from the Armenian border, in the autonomous Nakhchivan exclave.

Yerevan denied Baku’s statement, saying it proposed to Azerbaijan the establishment of a bilateral mechanism for investigating cases of cease-fire violations.

Azerbaijan and Armenia fought two wars – in the 1990s and 2020 – over the control of Karabakh, which had been illegally occupied by Armenians but is internationally recognized as part of Azerbaijan.

Most of the territory was liberated by Azerbaijan during a 44-day war in the fall of 2020, which ended after a Russian-brokered peace agreement that opened the door to normalization and talks on border demarcation.

Baku in September recaptured the mountainous enclave in a one-day offensive as separatists surrendered and some 150,000 Karabakh residents returned to Armenia.

Azerbaijan and Armenia have been working to sign a peace treaty since. The issue of opening transport links in the region, including the Zangezur corridor, a land route connecting Azerbaijan to Nakhchivan, has been a contentious issue in ongoing peace talks.

Baku argues that Azerbaijani citizens and cargo traveling to Nakhchivan via Armenia should not be subject to any controls, while Yerevan's position is that passages on that route should be in accordance with its own laws.

The sides have also sporadically exchanged fire along their troubled border in recent months, stoking concerns that an agreement could be further delayed.

Azerbaijani President Ilham Aliyev has said that reaching a peace agreement with Armenia is impossible until Armenia removes in its Constitution a problematic reference to the country's 1991 declaration of independence from the Soviet Union, which proclaims Armenia's unification with Karabakh as a national goal.

In response, Pashinyan last month said his country "needs a new constitution" because the current one "doesn't reflect citizens' vision of the relations with neighboring countries."

In May, Armenia returned to Azerbaijan four border villages that it had seized decades earlier, with Pashinyan saying the move was part of his efforts to secure peace with Azerbaijan.

In June, Pashinyan said Yerevan was ready to sign a peace agreement with Baku "within a month," while Aliyev said in July that the text of the agreement could be finalized within a matter of several months.