Hungary–Romania relations
During World War II, Hungary and Romania became allies and participated in the war against the Soviet Union. But after the coup on 23 August 1944 Romania switched sides and fought against Hungary. Consequently, Soviet and Romanian troops invaded Hungary, occupied Northern Transylvania by October 1944 and re-established the Romanian administration in the region in March 1945. The 1947 Treaty of Paris reaffirmed the borders between Romania and Hungary as originally defined in Treaty of Trianon 27 years earlier, thus confirming the return of Northern Transylvania to Romania.
Romania in World War II
Half of the estimated 270,000 to 320,000 Jews living in Bessarabia, Bukovina, and Dorohoi County in Romania were murdered or died between June 1941 and the spring of 1944, of wich between 45,000 and 60,000 Jews were killed in Bessarabia and Bukovina by Romanian and German troops, within months of the entry of the country into the war during 1941. Even after the initial killings, Jews in Moldavia, Bukovina and Bessarabia were subject to frequent pogroms, and were concentrated into ghettos from which they were sent to Transnistria, including camps built and run by the Romanian authorities.