Eventually, in 1940, Romania lost Bessarabia to the Soviet Union (USSR), regaining it in 1941 but losing it once again in 1944. The USSR established in part of Bessarabia the Moldavian SSR, which achieved independence in 1991 as the Republic of Moldova, developing since then a movement for unification with Romania. Today, the Day of the Union of Bessarabia with Romania is celebrated both in Romania, where it is an official holiday since 2017, and Moldova, including the legally Moldovan breakaway territory of Transnistria.