Beyond mutual defence, the CSTO also coordinates efforts in fighting the illegal circulation of weapons among member states and has developed law enforcement training for its members in pursuit of these aims. Members also use the organization to counter cyber warfare, narcotics trafficking, the illegal circulation of weapons, transnational crime, and terrorism.
According to Yulia Nikitina of the Moscow State Institute of International Relations, as of 2013, the CSTO has four types of collective forces. There are two regional groups (Russia-Belarus and Russia-Armenia) which are able to react to external military aggression; a 4,000-head Collective Rapid Deployment Force for Central Asia; a 20,000-head Collective Rapid Reaction Force, both of which are designed to react to situations short of interstate conflicts. There is also a collective peacekeeping force, including around 3,500 soldiers and officers and more than 800 civilian police officers.
The emergence of the CSTO can be explained in large part by the growing regionalization of international relations globally. Regional groupings like the CSTO help small, developing countries in particular confront global competition, as they allow the state to open up to the outside world while protecting national interests.
The CSTO is only the latest iteration of the older Collective Security Treaty, which took effect in 1994 and included Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, and Uzbekistan. Five years later, six of the nine—all but Azerbaijan, Georgia, and Uzbekistan—agreed to renew the treaty for five more years, and in 2002 those six agreed to create the Collective Security Treaty Organization as a military alliance. Uzbekistan again became a CSTO member in 2006 but then withdrew its membership in 2012.