In the first years after the Second World War, Socialist Yugoslavia was a close ally of the Soviet Union. However, increasing differences between the leaderships of the two countries led to an end of such cooperation and open hostilities, symbolised by the Resolution of the Cominform, published in 1948. Some Yugoslav communists supported the Soviet course, which turned them into enemies of the Yugoslav state and the Communist Party. Some of them decided to escape the country. Among them were some aviators, who had the best chance of escaping by using aircraft. Four confirmed cases of defection by air to Romania occurred between 1948 and 1951. The first defector was Major-General Pero Popivoda, who flew from Belgrade to Timisoara in August 1948. He later became the leader of Yugoslav communist emigrees in Eastern Europe. In 1949, Colonel Berislav Supek and Major Aleksandar Opojević of the 119th Transport Regiment of the Yugoslav Air Force forced the pilot of a transport plane on a regular flight, Milutin Obradović, to transport them to Timisoara. In 1950, Mijo Pušić, instructor at the Federal Gliding Centre of the Aeronautical Union of Yugoslavia at Vršac, also flew an airplane to Timisoara. It is unclear whether he did this on purpose or by accident. In 1951, Second Lieutenant Petar Mitrović of the 117th Fighter Regiment used a night training flight to defect to Romania. Except for Mitrović, all the other defectors were actively participating in the propaganda campaign led by the Soviet Union and its satellites against Yugoslavia and its leaders in the late 1940’s and early 1950’s. They worked for the Free Yugoslavia (Slobodna Jugoslavija) radio station in Bucharest, published articles in emigree newspapers, and participated in Soviet-led political gatherings and organisations. In the cases of Popivoda and Supek, their defections and later activity led to them being vilified in the Yugoslav press. Their activity was suspended after the normalisation of Yugoslav Soviet relations, starting in 1955. Among them, P. Popivoda died in the USSR in 1978; B. Supek returned to Yugoslavia; M. Obradović remained in Romania and worked as a journalist and film cameraman, occasionally visiting Yugoslavia. A. Opojević was killed in 1975 by agents of the Yugoslav State Security Service during the arrest of Yugoslav dissident Vlado Dapčević in Bucharest. It was not possible to determine the fate of Pušić and Mitrović.