The United States , United Kingdom and several other countries considered the annexation of Estonia by the USSR illegal following the Stimson Doctrine — a stance that made the doctrine an established precedent of international law . Although the US , the UK , the other Allies of World War II recognized the occupation of the Baltic states by USSR at Yalta Conference in 1945 '' de facto '' , they retained diplomatic relations with the exiled representatives of the independent Republic of Estonia , and never formally recognized the annexation of Estonia de jure
Yalta Conference
Yalta Conference
Estonian Soviet Socialist Republic