Lithuanian Soviet Socialist Republic in the context of "Soviet invasion of Poland"

The post-Soviet states, also referred to as the former Soviet Union or the former Soviet republics, are the independent sovereign states that emerged/re-emerged from the dissolution of the Soviet Union in 1991. Prior to their independence, they existed as Union Republics, which were the top-level constituents of the Soviet Union. There are 15 post-Soviet states in total: Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan. Each of these countries succeeded their respective Union Republics: the Armenian SSR, the Azerbaijan SSR, the Byelorussian SSR, the Estonian SSR, the Georgian SSR, the Kazakh SSR, the Kirghiz SSR, the Latvian SSR, the Lithuanian SSR, the Moldavian SSR, the Russian SFSR, the Tajik SSR, the Turkmen SSR, the Ukrainian SSR, and the Uzbek SSR. In Russia, the term "near abroad" (Russian: ближнее зарубежье, romanized: bližneye zarubežye) is sometimes used to refer to the post-Soviet states other than Russia.

Following the transition period and cessation of the existence of the Soviet Union, post-Soviet states and the international community de facto and de jure recognized Russia as the only continuator state to the Soviet Union as a whole, rather than to just the Russian SFSR including UN and UNSC membership (see agreements in Succession, continuity and legacy of the Soviet Union). The other post-Soviet states were recognized as successors only to their corresponding Union Republics and to international treaties concluded by the Soviet Union. All 12 post-Soviet states are successors of the Soviet Union, but not continuators.

Western Belorussia or Western Belarus (Belarusian: Заходняя Беларусь, romanized: Zachodniaja Biełaruś; Polish: Zachodnia Białoruś; Russian: Западная Белоруссия, romanized: Zapadnaya Belorussiya) is a historical region of modern-day Belarus which belonged to the Second Polish Republic during the interwar period. For twenty years before the 1939 invasion of Poland, it was the northern part of the Polish Kresy macroregion. Following the end of World War II in Europe, most of Western Belorussia was ceded to the Soviet Union by the Allies, while some of it, including Białystok, was given to the Polish People's Republic. Until the dissolution of the Soviet Union in 1991, Western Belorussia formed the western part of the Byelorussian Soviet Socialist Republic (BSSR). Today, it constitutes the west of modern Belarus.

Created by the USSR after the conquest of Poland, the new western provinces of Byelorussian SSR acquired from Poland included Baranavichy, Belastok, Brest, Vileyka and the Pinsk Regions. The majority of Belastok Region was returned to Poland and the rest of the regions were reorganized one more time after the Soviet liberation of Belarus into the contemporary western provinces of Belarus which include all of Grodno and Brest regions, as well as parts of today's Minsk and Vitebsk regions. Vilnius was returned by the USSR to the Republic of Lithuania which soon after that became the Lithuanian SSR.

Klaipėda (/ˈkleɪpɛdə/ CLAY-ped-ə; Lithuanian: [ˈklˠɐɪ̯ˑpʲeːdˠɐ] ) is a city in Lithuania on the Baltic Sea coast. It is the third-largest city in Lithuania, the fifth-largest city in the Baltic States, the capital of Klaipėda County, the only major seaport in the country and the busiest port in the Baltic States.

The city has a complex recorded history, partially due to the combined regional importance of the usually ice-free port at the mouth of the river Akmena-Danė [lt]. It was situated in Lithuania Minor and successively belonged to the State of the Teutonic Order, the Duchy of Prussia (at times under the suzerainty of the Polish–Lithuanian Commonwealth), the Kingdom of Prussia and the German Empire, within which it was the northernmost big city until it was placed under French occupation in 1919. From 1923, the city was part of Lithuania until its annexation by Nazi Germany in 1939, and after World War II it was part of the Lithuanian Soviet Socialist Republic. Klaipėda has remained within Lithuania since 1944.

Seventeen days after the German invasion of Poland in 1939, which marked the beginning of the Second World War, the Soviet Union entered the eastern regions of Poland (known as the Kresy) and annexed territories totalling 201,015 square kilometres (77,612 sq mi) with a population of 13,299,000. Inhabitants besides ethnic Poles included Belarusian and Ukrainian major population groups, and also Czechs, Lithuanians, Jews, and other minority groups.

These annexed territories were subsequently incorporated into the Lithuanian, Byelorussian, and Ukrainian Soviet Socialist Republics and remained within the Soviet Union in 1945 as a consequence of European-wide territorial rearrangements configured during the Tehran Conference of 1943 (see Western Betrayal). Poland was compensated for this territorial loss with the pre-War German eastern territories, at the expense of losing its eastern regions. The Polish People's Republic regime described the territories as the "Recovered Territories". The number of Poles in the Kresy in the year 1939 was around 5.274 million, but after ethnic cleansing in 1939-1945 by Nazi Germany, the Soviet Union and Ukrainian nationalist forces, Kresy consisted of approximately 1.8 million inhabitants. The post-World War II territory of Poland was slightly smaller than the pre-1939 land areas, shrinking by some 77,000 square kilometres (30,000 sq mi) (roughly equalling that of the territories of Belgium and the Netherlands combined).

The Ministry of National Defence of the Republic of Lithuania (Lithuanian: Lietuvos Respublikos krašto apsaugos ministerija) is the government institution of Lithuania responsible for the organization of national defence. It was originally established in 1918 upon the independence of Lithuania and reestablished following the end of Soviet rule in 1991.