The three Baltic countries, or the Baltic states – Estonia, Latvia, and Lithuania – are held to have continued as legal entities under international law while under the Soviet occupation from 1940 to 1991, as well as during the German occupation in 1941–1944/1945. The prevailing opinion accepts the Baltic thesis of illegal occupation and the actions of the USSR are regarded as contrary to international law in general and to the bilateral treaties between the USSR and the three Baltic countries in particular.

Estonia, officially the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, and to the east by Lake Peipus and Russia. The territory of Estonia consists of the mainland, the larger islands of Saaremaa and Hiiumaa, and over 2,300 other islands and islets on the eastern coast of the Baltic Sea, covering a total area of 45,335 square kilometres (17,504 sq mi). Tallinn, the capital city, and Tartu are the two largest urban areas of the country. Estonian, a Uralic language, is the indigenous and official language of Estonia, and it is the first language of the majority of its population of 1.3 million.