At Janka Puszta training facility in Hungary, IMRO terrorists trained Ustaše operatives in bomb-making and in conspirational activities. The Ustaše put that knowledge to immediate use, carrying out about half-dozen assassinations of Yugoslavian officials or pro-Serb civilians. They carried out a dozen bombings of trains, including the Orient Express, and other public targets during the first four years of their existence. This caused the Yugoslav Government to complain to the League of Nations and forced Hungary to close down Janka Pusta Ustaše training camp. Internal power struggle, and discovery that Perčec's mistress was a Yugoslav police informant, will lead to the Perčec assassination by Pavelić in 1933.