Belarus delivered advanced weapons to Azerbaijan for years, despite being in a Russia-led security alliance with Armenia, Politico reported on June 13, citing a cache of leaked documents.
Armenia's Prime Minister Nikol Pashinyan announced on June 12 that Armenia was to withdraw from the Collective Security Treaty Organization (CSTO), a military alliance made up of Russia, Armenia, Belarus, Kazakhstan, Tajikistan, and Kyrgyzstan.
"We will leave," Pashinyan told the Armenian parliament, accusing the CSTO of plotting "against us with Azerbaijan," which seized the region of Nagorno-Karabakh in 2023.
Article 4 of the CSTO Treaty states that if a member state experiences aggression, then all member states must come to its aid, in a similar way to NATO's Article 5 principles.
"We will decide when to leave. We won't come back, there is no other way," Pashinyan said.
According to Politico, a cache of letters, diplomatic notes, bills of sale, and export passports show that Belarus supplied "advanced military hardware to Azerbaijan between 2018 and 2022."
The move is likely regarded as a "bitter betrayal" by Armenia as the supplies gave Baku the "upper hand" in its conflict with Yerevan, Politico said.
The help Belarus reportedly provided to Azerbaijan ranged from supplying artillery targeting equipment and new gear for electronic warfare to modernizing artillery equipment.
The services offered included modernizing older artillery equipment and providing new gear used for electronic warfare and drone systems, Politico said.
Pashinyan's announcement on June 12 is the latest in a series of steps Armenia has taken to distance itself from the CSTO.
Armenia's Foreign Ministry said in May that Armenia will not partake in the financing of the CSTO. In March, Yerevan threatened to leave if the military alliance failed to address Armenia's collective security concerns.
Pashinyan said in February that Armenia had "frozen" its participation in the Russian-led CSTO because it failed to uphold its objectives regarding Armenia.
The remarks come amid a growing rift between Yerevan and Moscow, which was exacerbated when Russian "peacekeepers" in Nagorno-Karabakh did not prevent Azerbaijan's armed seizure of the region.