The article provides a general overview of the means used to legalize and legitimize the expansionist policy of the Russian Federation through the history. It is emphasized that, basically, they are (pseudo) legal instruments - forms and means that imitate the external features of certain legal forms in order to create a simulacrum of social and legal reality and substitute them for legal institutions. Such a simulacrum is provided mainly with the imitation of the right of the people for self-determination, which is intended to simulate its realization and which takes place on three planes: subject – formation of an imaginary community, a simulacrum of the people; action – holding a pseudo-referendum; result – simulation of the secession process, of the procedure for proclaiming republics with the subsequent formal “declaration of sovereignty”. The creation of quasi-sovereign “puppet” republics to achieve certain political goals other than officially declared has been used by the USSR for political purposes since the very beginning. The latter is illustrated by examples from the history of the USSR, namely the creation of the Moldavian Autonomous Republic within the Ukrainian SSR. The decision to create it was made behind the scenes by communist forces, agreed upon by the highest communist party bodies of Ukraine and Moscow, and the dispute that arose between them over the organizational form was resolved unilaterally by the Moscow Communist Party, which further demonstrates the non-sovereignty of the Ukrainian Soviet authorities in the USSR. The purpose of the formation was foreign policy (the prospect of joining Romanian Basarabia) and domestic policy (strengthening Soviet power in the region). Only after these approvals did the republic become legally established, through a decision made by the democratic authorities - the All-Ukrainian Central Executive Committee on October 12, 1924, in Kharkiv. It was only on April, 19-23, 1925, that the 1st All-Moldovan Congress of Soviets took place. The Constitution of the Ukrainian SSR already referred to the establishment of Moldovan autonomy as the unification of the Ukrainian SSR with the Moldovan people on the basis of recognition of the right of all nations to self-determination. The author believes that the use of pseudo-legal forms and means to legitimize and legalize expansionist policies was a common means of the USSR and modern Russia; in none of the historical precedents did the Soviets and Russian authorities take responsibility for the direct management of the occupied territories, carrying it out through the mediation of agents and collaborators who imitated the people’s will. The author concludes that the widespread use of pseudo-legal forms can be called a characteristic feature of the expansionist policy of the Soviet and now the Russian authorities when trying to legalize and legitimize actions that are in fact occupations. It is worth noting that the use of such specific forms of legalization and legitimation is possible only if there is a local population, some of which is loyal to the policies of the occupying power or has dual loyalties and identities. This explains the spread and viability of such pseudo-legal means in the territory of the former USSR, a state where dual loyalty and identity have been nurtured in the population for several generations. The author emphases that the prerequisites for such a specific occupation practice of the Russian Federation are laid down much earlier than the military occupation itself –by a common information space, common language and memory practices, and acommon cultural space. This should also be taken into account in Ukraine’s information policy as part of a comprehensive response to Russia’s occupationpractices. Key words: sovereignty, quasi-sovereignty, pseudo-republics, secession, Ukraine, USSR, legitimation, legalization.