On August 23, 1990, Supreme Council adopted the Declaration of State Sovereignty of Armenia proclaiming the Armenian SSR abolished and the establishment of the Republic of Armenia. Armenia refused to sign the New Union Treaty. After the failed August putsuch, the people of Armenia voted in a referendum to proclaim independence from the Soviet Union on September 21, 1991. Levon Ter-Petrosyan was elected the first president of Armenia in November 1991. On December 21, 1991, Armenia joined the Commonwealth of Independent States (CIS). Armenia gained independence formally on December 26 in connection with the dissolution of the USSR.