premise: Ukrainian Soviet Socialist Republic was in the UN until 1987.
hypothesis: Ukrainian Soviet Socialist Republic . Ukrayina [ ukrɑˈjinɑ ] ) , was one of the constituent republics of the Soviet Union from its inception in 1922 to its breakup in 1991 . Upon the Soviet Union 's dissolution and perestroika , the Ukrainian SSR was transformed into the modern nation-state and renamed itself to Ukraine , although Ukraine 's new constitution was only ratified on 28 June 1996 . According to the Soviet Census of 1989 the republic had a population of 51,706,746 inhabitants , which fell sharply after the breakup of the Soviet Union .