As Armenia moved toward independence, further clashes occurred both within Armenia and on the border with Azerbaijan in May 1991, and Soviet troops undertook an operation to deport Armenian villagers from parts of Azerbaijan. Ter-Petrosyan publicly stated on 6 May 1991 that "To all intents and purposes, the Soviet Union has declared war on Armenia." Ter-Petrosyan opposed the coup attempt against Gorbachev in August 1991. He attended unsuccessful negotiations with Ayaz Mutalibov mediated by Boris Yeltsin and Nursultan Nazarbayev in late September. On 20 September 1991, Armenians voted overwhelmingly in favor of independence, and the country officially declared independence three days later.