The Latvian Soviet Socialist Republic was a republic of the Soviet Union in 2012.
The Latvian Soviet Socialist Republic ( Latvian SSR ; Latvijas Padomju Sociālistiskā Republika Латвийская Советская Социалистическая Республика , Latviyskaya Sovetskaya Sotsialisticheskaya Respublika ) , also known as Soviet Latvia or Latvia , was a republic of the Soviet Union . It was established on 21 July 1940 , during World War II , as a Soviet puppet state in the territory of the previously independent Republic of Latvia after it had been occupied on June 17 , 1940 by the Soviet Army , in conformity with the terms of the 23 August 1939 Molotov -- Ribbentrop Pact . Following the Welles Declaration of July 23 , 1940 , the annexation of Latvia into the Soviet Union ( USSR ) on 5 August 1940 was not recognized as legitimate by the United States , the European Community , and recognition of it as the nominal fifteenth constituent republic of the USSR was withheld for five decades . Its territory was subsequently conquered by Nazi Germany in June -- July 1941 , before being retaken by the Soviets in 1944 -- 1945 . The full independence of the Republic of Latvia was restored on 21 August 1991 , during the 1991 Soviet coup d'état attempt and fully recognized by the Soviet Union on 6 September 1991 .