Under the deal, Armenia ceded swathes of territory it had controlled for decades, and Moscow deployed about 2,000 Russian peacekeepers to oversee the fragile truce.
With Moscow increasingly isolated on the world stage following its February invasion of Ukraine, the United States and the European Union have taken a leading role in mediating the Armenia-Azerbaijan normalisation process.
On Sunday, the foreign ministers of Armenia and Azerbaijan met in Geneva where they began drafting the text of a future peace treaty.
When the Soviet Union collapsed in 1991, ethnic Armenian separatists in Nagorno-Karabakh broke away from Azerbaijan. The ensuing conflict claimed around 30,000 lives.