This study analyzes the legal nature and background of regional integration in the framework of the Commonwealth of Independent States, the Russian-Belarusian Union, the Single Economic Space, the Eurasian Economic Community and the Collective Security Treaty Organization. It also deals with the RIAs created outside of the Russian control in the format of GUAM and among Central Asian countries. Finally, the book contains conclusive remarks attempting to assess the possibility of the creation of an Eurasian Union.