the incorporation of Bessarabia into Romania and throughout the entire interwar period engaged in attempts to undermine Romania and diplomatic disputes with the government in Bucharest over this territory. The Molotov–Ribbentrop Pact was signed on August 23, 1939. By Article 4 of the secret Annex to the Treaty, Nazi Germany recognized Bessarabia as belonging to the Soviet "sphere of interest". In the spring of 1940, Western Europe was overrun by Germany. With world attention focused on those events, on June 26, 1940, the USSR issued a 24-hour ultimatum to Romania, demanding immediate cession of Bessarabia and Northern Bukovina under threat of war. Romania was given four days to evacuate its troops and officials. The two provinces had an area of , and were inhabited by about 3.75 million people, half of them Romanians, according to official Romanian sources. Two days later, Romania yielded and began evacuation. During the evacuation, from June 28 to July 3, groups of local Communists and Soviet sympathizers attacked the retreating forces and civilians who chose to leave. Many members of the minorities (Jews, ethnic Ukrainians and others) joined in these attacks. The Romanian Army was also attacked by the Soviet Army, which entered Bessarabia before the Romanian administration finished retreating. The casualties reported by the Romanian Army during those seven days consisted of 356 officers and 42,876 soldiers dead or missing. On August 2, the Moldavian Soviet Socialist Republic was established on most of the territory of Bessarabia, merged with the western parts of the former Moldavian ASSR. Bessarabia was divided between the Moldavian SSR (65% of the territory and 80% of the population) and the Ukrainian SSR. Bessarabia's northern and southern districts (now Budjak and parts of the Chernivtsi oblast) were allotted to Ukraine, while some territories (4,000 km2) on the left (eastern) bank of Dniester (present Transnistria), previously part of Ukraine, were allotted to Moldavia. Following the Soviet takeover, many Bessarabians, who were accused of supporting the deposed Romanian administration, were executed or deported to Siberia and Kazakhstan. Between September and November 1940, the ethnic Germans of Bessarabia were offered resettlement to Germany, following a German-Soviet agreement. Fearing Soviet oppression, almost all Germans (93,000) agreed. Most of them were resettled to the newly annexed Polish territories. On June 22, 1941 the Axis invasion of the Soviet Union commenced with Operation Barbarossa. Between June 22 and July 26, 1941, Romanian troops recovered Bessarabia and