During World War II, Ukrainian became an area of of German - Polish and German - Soviet conflicts.
On August 23, 1939 Germany and Russia signed a pact, which provided for the division of Poland and the annexation of the Baltic states by the USSR. On September 1, 1939 Germany invaded Poland. German armies occupied the western and central parts of Poland and the Soviets took Ukrainian and Belorusian territories within a matter of three weeks. The boundary between German and Soviet territories was fixed at the Sian - Solokia - Buh Rivers — the Sian region (Posiannia), the Lemko region and western Pidliassia (Pidlissia) under German control while the rest went to the Soviet Union, which incorporated the territory into the Ukrainian SSR, except for the northern part of Polissia, which was joined to the Belorussian SSR. In an agreement between the USSR and Rumania on June 28, 1940, northern Bukovyna and Bessarabia were ceded to the USSR. Northern Bukovyna and the Khotyn, Akkerman and Izmail counties of Bessarabia were incorporated into the Ukrainian SSR. The remaining portion of Bessarabia was constituted as an autonomous region within the Ukrainian SSR as the Moldavian ASSR. ...

The proclamation of the restablishment of Ukraine`s independence August 24, 1991, which was confirmed overwhelmingly in a national referendum December 1, 1991 (91% Of the population of Ukraine voting for independence) was the culmination of the liberation struggle started by Ukrainian cossacks in the early part of the 17th century and continued until the present.
The immediate circumstances leading to this momentous step were M. Gorbachev's initiation of "glasnost" and reforms within the USSR. Originally these reforms were started as an attempt to save the power of the Cominunist Party and the Soviet Union. However, these reforms had the opposite effect. Subjugated nations within the USSR seized this opportunity to free themselves from both Communist and Russian oppression. ...