However, the situation in Bessarabia would change after the signing of the Molotov–Ribbentrop Pact between the Soviet Union (USSR) and Nazi Germany, in which the latter expressed its disinterest in the region. This allowed the USSR to send an ultimatum to Romania, which was now diplomatically isolated with the outbreak of World War II, on 26 June 1940 in which it demanded Bessarabia and also Northern Bukovina. After Romania accepted it, and the USSR occupied these territories, ending Romanian rule in the zone. Bessarabia was organized and split between the Ukrainian SSR and the new Moldavian SSR, which gained independence in 1991 as Moldova. Ever since, there has been a minoritary but growing movement to reunite the region with Romania, with supporters in Romania and Moldova commemorating the day of the union, 27 March, on the Day of the Union of Bessarabia with Romania.