Six Bulgarian citizens were arrested on March 18, 2021 and charged with espionage for obtaining classified information about the defense plans of Bulgaria, NATO, the European Union, the US embassy in Sofia and the CIA and providing them to Russian embassy officials in Sofia. The network involved three employees of the Ministry of Defense - the deputy head of the budget department of the ministry and two active military intelligence officers. The head of the network was 74-year-old Ivan Iliev, former head of the Bulgarian Military Intelligence Service and a graduate of the Main Directorate of the General Staff of the USSR Armed Forces. His wife, who has dual Bulgarian and Russian citizenship, was also involved. The discovery came just before the April 4 parliamentary elections, in which Boiko Borisov's government had two opponents: the pro-Russian left-wing party and incumbent President Rumen Radev, who also expressed pro-Russian sympathies. On March 19, Bulgaria's attorney general publicly announced the allegations and revealed details of the search operation, including telephone conversations and video recordings. According to Bulgarian authorities, this was the most important spy network since 1990. According to Bulgarian National Television, the Russian diplomats involved are Maxim Ribkin, the first secretary in the Russian embassy, and Alexander Zinkin, the second secretary. Sofia allegedly asked the two to leave Bulgaria.