Latvia took the position that it did not need to follow the process of secession delineated in the Soviet constitution, arguing that since the annexation was illegal and unconstitutional, it was merely reasserting an independence that still existed under international law. However, the central power in Moscow continued to regard Latvia as a Soviet republic in 1990–1991. In January 1991, Soviet political and military forces tried unsuccessfully to overthrow the Republic of Latvia authorities by occupying the central publishing house in Riga and establishing a Committee of National Salvation to usurp governmental functions. During the transitional period Moscow maintained many central Soviet state authorities in Latvia. In spite of this, seventy-three percent of all Latvian residents confirmed their strong support for independence on March 3, 1991, in a non-binding advisory referendum. A large number of ethnic Russians also voted for the proposition. The Republic of Latvia declared the end of the transitional period and restored full independence on 21 August 1991 in the aftermath of the failed Soviet coup attempt. Latvia, as well as Lithuania and Estonia de facto ceased to be parts of the USSR four months before the Soviet Union itself ceased to exist (26 December 1991). Soon, on 6 September, the independence of three Baltic states was recognized by the USSR. Today's Republic of Latvia and other Baltic states consider themselves to be the legal continuation of the sovereign states whose first independent existence dates back to 1918–1940, and does not accept any legal connection with the former Latvian SSR which had been occupied and annexed into USSR 1940–1941 and 1944–1991. Since independence, the Communist Party of the Latvian SSR was discontinued, and a number of high-ranking Latvian SSR officials faced prosecution for their role in various human rights abuses during the Latvian SSR regime. Latvia later joined NATO and the European Union in 2004.