'It is all the fault of Lithuanian provocateurs…'. Annexation of Lithuania by USSR in summer 1940 as described in diplomatic documents and propaganda materials

The research problem addressed in this paper is the issue of the process of the accession of the Republic of Lithuania to the Soviet Union in the summer of 1940 and the political context of this event. There is much historical and political controversy nowadays around the history of Kremlin politics in 1939–1941, but recently the subject of annexation of Lithuania has not been discussed, and the issue of relations and diplomatic relations between the two countries has not been described in detail in Polish historiography so far. The research question was formulated as follows: why, in spite of the October 1939 Mutual Assistance Treaty, did Moscow decide to change the status quo and directly annex the neighbouring country, disregarding the considerable number of alternative scenarios and extensive possibilities of controlling Lithuania’s policy? The research was conducted by analysing the documents of the diplomatic services of both countries (among which diplomatic correspondence occupies a special place), the then Soviet press from the point of view of the propaganda message used, as well as using memoiristic sources. As a result of the conducted research, no definite reasons for initiating the process of annexation of Lithuania by the USSR were defined, but a number of factors that may have a significant impact on the Kremlin’s move were revealed. These include the successes of the Third Reich in the Second World War at that time, which, according to Moscow, could threaten the position of the USSR in the Baltic States and the achievements made, as well as the Kremlin’s far-reaching imperial plans and the search for borders in the region