Ukrainian Soviet Socialist Republic
Eventually, after the creation of the Communist Party (Bolshevik) of Ukraine in Moscow, a third Ukrainian Soviet government was formed on 21 December 1919 that initiated new hostilities against Ukrainian nationalists as they lost their military support from the defeated Central Powers. Eventually, the Red Army ended up controlling much of the Ukrainian territory after the Polish-Soviet Peace of Riga. On 30 December 1922, along with the Russian, Byelorussian, and Transcaucasian republics, the Ukrainian SSR was one of the founding members of the Union of Soviet Socialist Republics (USSR).
Eastern Bloc politics
In 1922, the Russian Soviet Federative Socialist Republic (RSFSR), the Ukrainian SSR, the Byelorussian SSR and the Transcaucasian SFSR, approved the Treaty of Creation of the USSR and the Declaration of the Creation of the USSR, forming the Soviet Union. At the end of World War II by mid-1945, all eastern and central European capitals were controlled by the Soviet Union. During the final stages of the war, the Soviet Union began the creation of the Eastern Bloc by directly annexing several countries as Soviet Socialist Republics that were originally effectively ceded to it by Nazi Germany in the Molotov–Ribbentrop Pact. Eastern Poland, eastern Finland, the Baltics, Bukovina, and Bessarabia, now called Moldova, were forcibly incorporated into the Soviet Union. The eastern Polish territories remain part of Ukraine and Belarus as of the early 21st century.