The Armenian post issued a stamp dedicated to the 20th anniversary of the CSTO – Collective Security Treaty Organization. The Collective Security Treaty Organization is an intergovernmental military alliance which was signed on 15 May 1992.
On 7 October 2002, the Presidents of Armenia, Belarus, Kazakhstan, Kyrgyzstan, Russia and Tajikistan signed a charter in Tashkent founding the CSTO.
The CSTO charter reaffirmed the desire of all participating states to abstain from the use or threat of force. Signatories would not be able to join other military alliances or other groups of states, while aggression against one signatory would be perceived as an aggression against all. To this end, the CSTO holds yearly military command exercises for the CSTO nations to have an opportunity to improve inter-organization cooperation.
The largest-scale CSTO military exercise held to date were the "Rubezh 2008" exercises hosted in Armenia where a combined total of 4,000 troops from all 7 constituent CSTO member countries conducted operative, strategic, and tactical training with an emphasis towards furthering efficiency of the collective security element of the CSTO partnership.