Fighting broke out on September 27. Since then, more than 400 people have been killed in fighting over the contested region. Nagorno-Karabakh is officially part of Azerbaijan, but under control of ethnic Armenian forces backed by Armenia since the end of a separatist war in 1994.
Russian Defense Minister Sergei Shoigu appealed for the Azeri and Armenian defense ministers to "fully meet the commitments" of the humanitarian ceasefire.
Targeting civilian areas?
The missile launch systems were deployed in areas of Armenia bordering the Kalbajar district of Azerbaijan in the Nagorno-Karabakh region.
The first launch site was aiming at the Azerbaijani cities of Ganja, Mingachevir and other populated areas, according to claims from the Azerbaijani defense ministry.
However, Armenia denied that was targeting civilians. "The attack was carried out based on the mere assumption that the subject equipment was allegedly going to strike at Azerbaijan's civilian settlements," defense ministry spokeswoman Shushan Stepanyan said on Twitter.
Throughout Wednesday, both Azerbaijan and Armenia claimed the other side was violating cease-fire terms and engaging in provocations.
Azeri President Ilham Aliyev Wednesday said that Azerbaijan was continuing a military operation to free territory in Nagorno-Karabakh, Russian news agency Interfax reported. Aliyev also accused Armenia of trying to attack its gas and oil pipelines, in an interview with Turkish broadcaster Haberturk. He warned of a "severe" response.
Armenia's Prime Minister Nikol Vovayi Pashinyan gave an address to the nation, calling for Azerbaijan and its supporter, Turkey, "to stop their aggression."
The Nagorno-Karabakh defense ministry accused Azeri forces of launching artillery and rocket attacks in several areas.
Defense officials in the enclave said their forces had shot down an Azeri Su-25 fighter jet, a claim Azerbaijan has rejected.
Turkey arms sales
Meanwhile, details have emerged regarding an upsurge in Turkey's military exports to Azerbaijan in recent months.
Arms sales from Ankara to its ally have risen six-fold this year, with sales of drones and other military equipment rising to $77 million (€65.5 million) last month alone, prior to the outbreak of conflict over Nagorno-Karabakh.
The data compiled by the Turkish Exporters' Assembly, which groups more than 95,000 exporting firms across 61 sectors, shows Azerbaijan bought $123 million worth of defense and aviation equipment from Turkey during the first nine months of 2020.