In 1939, the secret appendix to the Molotov–Ribbentrop Pact assigned Bessarabia to the Soviet Union's sphere of influence and, in June 1940, the Soviets issued an ultimatum demanding the transfer of Bessarabia and Northern Bukovina. King Carol II of Romania acquiesced and the area was annexed. Central and northern Bessarabia formed the center of the new Moldavian Soviet Socialist Republic but part of the south, now known as Budjak, was apportioned to the Ukrainian SSR. The commission that decided the administrative border between the Ukrainian SSR and Moldavian SSR inside the Soviet Union was chaired by Nikita Khrushchev, the then leader of the Ukrainian SSR and the future USSR leader who would add Crimea to the Ukrainian SSR.