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.
Military history of Romania
Romania reached its zenith during the inter-war period. After World War II, it was reduced to its modern borders and fell in the Soviet sphere of influence. The revolution of 1989 ended Communism and the geopolitical mutations in the region after the collapse of the Soviet Union paved the way for European integration, economically, politically, and militarily. Today, the Romanian army participates in peacekeeping missions with its NATO allies in Afghanistan, Bosnia, Kosovo and elsewhere.