Collective Security Treaty Organization

The Collective Security Treaty Organization (CSTO; Russian: Организация Договора о коллективной безопасности (ОДКБ), romanized: Organizatsiya dogovora o kollektivnoy bezopasnosti, ODKB) is an intergovernmental military alliance in Eurasia consisting of six post-Soviet states: Armenia, Belarus, Kazakhstan, Kyrgyzstan, Russia, and Tajikistan. The Collective Security Treaty has its origins in the Soviet Armed Forces, which was replaced in 1992 by the United Armed Forces of the Commonwealth of Independent States, and was then itself replaced by the successor armed forces of the respective independent states. Former members of the CSTO military alliance were Azerbaijan, Georgia and Uzbekistan.

Similar to Article 5 of the North Atlantic Treaty and the Inter-American Treaty of Reciprocal Assistance, Article 4 of the Collective Security Treaty (CST) establishes that an aggression against one signatory would be perceived as an aggression against all. The 2002 CSTO charter reaffirmed the desire of all participating states to abstain from the use or threat of force. Signatories are prohibited from joining other military alliances.