Following the dissolution of the Soviet Union, the militaries of a number of former Soviet republics have continued to operate the MiG-29, the largest of which is the Russian Air Force. The Russian Air Force wanted to upgrade its existing fleet to the modernised MiG-29SMT configuration, but financial difficulties have limited deliveries. The MiG-29 has also been a popular export aircraft; more than 30 nations either operate or have operated the aircraft to date. As of 2013 the MiG-29 was still in production by Mikoyan, a subsidiary of United Aircraft Corporation (UAC) since 2006.