The two South Caucasus nations, former Soviet states, have fought multiple wars since the 1980s when Nagorno-Karabakh, an ethnically Armenian region broke away from Azerbaijan.

But hurdles remain. Azerbaijan also said Armenia’s constitution must “eliminate the claims against the sovereignty and territorial integrity of Azerbaijan,” as a prerequisite to allow for the signing of the peace treaty.

Armenian Prime Minister Nikol Pashinyan and Russian President Vladimir Putin speak at a summit of leaders of nations, which are members of the Commonwealth of Independent States (CIS), at the Kremlin in Moscow,