Board Thread:General Discussion/@comment-6747658-20130401084750/@comment-8245466-20130701224706

Well Ocelot joined FOXHOUND after the collapse of the Soviet Union, but we've known since MGS 3 that he'd been working for the CIA long before that. Then, there's also Zadornov, who was a KGB agent who was also working for Cipher for some unknown reason. There seems to be no shortage of Soviet agents willing to switch sides, probably because they are more realistic about the outcome of the Cold War than people like Volgin or Gurlukovich.

Also, consider that Camp Omega is technically on Communist soil. It wouldn't be hard to convince a Soviet agent to walk right into camp and start working for you. Either way, Mantis has to somehow get from the Soviet Union over to the United States and start working for XOF.