Ukrainian Soviet Socialist Republic
The Ukrainian Soviet Socialist Republic (Ukrainian SSR or UkrSSR or UkSSR; , УРСР ; , УССР ; see "Name" section below), also known as the Soviet Ukraine, was one of the constituent republics of the Soviet Union from the Union's inception in 1922 to its breakup in 1991. The republic was governed by the Communist Party of Ukraine as a unitary one-party socialist soviet republic.
Polish–Ukrainian War
In the beginning of the Second World War, the area was annexed by the Soviet Union and attached to Ukraine, which at that time was a republic of the Soviet Union. According to the Yalta Conference decisions, while the Polish population of Eastern Galicia was resettled to Poland, the borders of which were shifted westwards, the region itself remained within the Soviet Ukraine after the war and currently forms the westernmost part of now independent Ukraine.