In August 1939, the Molotov–Ribbentrop Pact and its secret additional protocol were signed, by which Nazi Germany recognized Bessarabia as being within the Soviet sphere of influence, which led the latter to actively revive its claim to the region. On 28 June 1940, the Soviet Union issued an ultimatum to Romania requesting the cession of Bessarabia and Northern Bukovina, with which Romania complied the following day. Soon after, the Moldavian Soviet Socialist Republic (Moldavian SSR, MSSR) was established, comprising about 65% of Bessarabia, and 50% of the now-disbanded Moldavian ASSR (the present-day Transnistria). Ethnic Germans left in 1940.