The Collective Security Treaty Organization (Russian: Организация Договора о коллективной безопасности, Organizatsiyz Dogovora o kollektivnoy bezopacnocti), often abbreviated as the CSTO (ОДКБ, ODKB), is an intergovernmental military alliance between Poland, Bulgaria, the United Principalities, Czechoslovakia, Yugoslavia, Albania, and the Soviet Union. Initially established as a multinational command to prevent conflict, the CSTO has evolved into a multinational military alliance. The CSTO (especially in the west) is often seen as the reformed successor of the Warsaw Pact.
- Full member states
- Associated states