In this interwar period IMRO led by Aleksandrov and later by Mihailov took actions against the former left-wing assassinating several former members of IMORO's Sandanist wing, who meanwhile had gravitated towards the Bulgarian Communist Party and Macedonian Federative Organization. Gjorche Petrov was killed in Sofia in 1922, Todor Panitsa (who previously killed the right-wing oriented Boris Sarafov and Ivan Garvanov) was assassinated in Vienna in 1924 by Mihailov's future wife Mencha Karnichiu. Dimo Hadjidimov, Georgi Skrizhovski, Alexander Bujnov, Chudomir Kantardjiev and many others were killed in the events of 1925. Meanwhile, the left-wing later did form the new organisation based on the principles previously presented in the May Manifesto. The new organization which was an opponent to Mihailov's IMRO was called IMRO (United) was founded in 1925 in Vienna. However, it did not have real popular support and remained based abroad with no revolutionary activities in Macedonia. Mihailov's group of young IMRO cadres soon got into conflict with the older guard of the organization. The latter were in favour of the old tactic of incursions by armed bands, whereas the former favoured more flexible tactics with smaller terrorist groups carrying selective assassinations. The conflict grew into a leadership struggle and Mihailov soon, in turn, ordered the assassination in 1928 of a rival leader, General Aleksandar Protogerov, which sparked a fratricidal war between "Mihailovists" and "Protogerovists". The less numerous Protogerovists soon became allied with Yugoslavia and certain Bulgarian military circles with fascist leanings and who favoured rapprochement with Yugoslavia. The policy of assassinations was effective in making Serbian rule in Vardar Macedonia feel insecure but in turn provoked brutal reprisals on the local peasant population. Having lost a lot of popular support in Vardar Macedonia due to his policies, Mihailov favoured the "internationalization" of the Macedonian question.