Notwithstanding the annexation by the Soviet Union in 1940, it is therefore correct to speak of the occupation of the Baltic states, referring in particular to the absence of Soviet legal title. The prolonged occupation was an unorthodox one. Until 1991, the status of the three countries resembled the classical occupation in important ways: external control by an internationally unsanctioned force and a conflict of interest between the foreign power and the inhabitants. However, in other aspects the situation was very different from a classical occupation. Both the fact of the incorporation of the Baltic states to the USSR as Soviet republics without qualification, and the long duration of the Soviet rule challenge the applicability of all rules on occupation from the practical point of view. Despite the fact of annexation, the presence of the USSR in the Baltic states remained an occupation "sui generis".