borders of the
Polish–Lithuanian Commonwealth also indicated While the Treaty of Riga led to a two-decade stabilisation of Soviet-Polish relations, conflict was renewed with the
Soviet invasion of Poland during
World War II. The treaty was subsequently overridden after a decision by war's Allied powers to change Poland's borders once again and
transfer the populations. In the view of some foreign observers, the treaty's incorporation of significant minority populations into Poland led to seemingly insurmountable challenges, because the newly formed organizations such as
OUN engaged in terror and sabotage actions across ethnically mixed areas to inflame conflict in the region. Nevertheless, many groups representing national minorities welcomed Piłsudski's return to power in 1926 providing opportunities to play a role in the Polish government. The populations separated from Poland by the new Polish-Soviet border experienced a different fate from their fellow citizens. Ethnic Poles left within Soviet borders were subjected to discrimination and property confiscation. At least 111,000 were summarily executed in
the NKVD operation in 1937/38, preceding other ethnic repression campaigns perpetrated during World War II, while others were exiled to different regions of the Soviet Union. Belarusians and Ukrainians, having failed to create their own states, were subjects of repression in the Soviet Union, and even liquidation e.g.
Executed Renaissance or
persecuted kobzars and bandurists. Belarusians and Ukrainians living on the Polish side of the border were subjected to
Polonization; which contributed to the rise of
Ukrainian nationalist organisations and the adoption of
terrorist tactics by Ukrainian extremists. The Soviet Union, although thwarted in 1921, would see its sphere of influence expand as a result of
World War II. After the Soviet Union established its control over the
People's Republic of Poland, the
Polish-Soviet border was moved westwards in 1945 to roughly coincide with the
Curzon Line. This shift was accompanied by large
population transfers which led to the expulsion of the Poles living east of the new border, and also
moved most of the Ukrainian minority remaining in Poland to the
former German territories that were ceded to Poland in compensation. The unified Belarusian and Ukrainian territories were fully incorporated into the USSR. However, in 1989, Poland would regain its full sovereignty, and soon afterwards, with the
fall of the Soviet Union,
Belarus and
Ukraine would go on to become independent nations. == See also ==