Armenia confirmed its independence in a referendum on 21 September 1991 after the unsuccessful coup attempt in Moscow by the CPSU hardliners. Greece became the first country to recognize the newly minted Armenian nation a few days later. Tensions between Armenia and Nagorno-Karabakh on the one hand and Azerbaijan on the other continued to escalate, ultimately leading to the outbreak of the First Nagorno-Karabakh War. Despite a cease-fire in place since 1994, the parties have yet to resolve the Nagorno-Karabakh conflict. The Soviet Union itself ceased to exist on December 26, 1991, and Armenia became an sovereign independent state in the international stage. The United States recognized Armenia's independence a day before.