Despite Armenia's disengagement and growing questions about its effectiveness, the Collective Security Treaty Organization (CSTO) continues to develop its military cooperation mechanisms and adapt to contemporary security challenges. Recent joint exercises, efforts to improve communications and command systems, and growing attention to threats such as unmanned aerial vehicles indicate that the organization is attempting to incorporate lessons from modern conflicts, particularly the war in Ukraine. These developments provide a basis for assessing the CSTO's current military capabilities and its efforts to maintain regional relevance.

This raises the central question of whether the CSTO's military modernization reflects a meaningful improvement in its ability to function as a collective-defence alliance or primarily represents incremental adaptation without deeper operational integration. Although the organization continues to develop its capabilities and expand military cooperation, its effectiveness remains constrained by Russia's dominance, divergent interests among member states, and the limited evidence that joint exercises translate into reliable collective action during major security crises.

The Collective Security Treaty Organization (CSTO) originated from the Collective Security Treaty signed in Tashkent on 15 May 1992 by Armenia, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, and Uzbekistan. Following the dissolution of the Soviet Union, the treaty provided a framework for maintaining military cooperation among newly independent states. Azerbaijan, Belarus, and Georgia joined in 1993, and the treaty entered into force in 1994. However, Azerbaijan, Georgia, and Uzbekistan did not extend their participation in 1999, while Uzbekistan subsequently rejoined in 2006 before withdrawing again in 2012. These changes reflected the differing security priorities and foreign-policy orientations of the post-Soviet states.

In 2002, the member states formally established the CSTO as an international regional organization and adopted its charter, creating permanent institutional structures for political consultation and military cooperation. Its mandate encompasses collective defence, military coordination, counterterrorism, combating extremism and drug trafficking, and addressing other transnational security threats. The organization also developed collective rapid-reaction and peacekeeping capabilities, supported by joint exercises intended to improve coordination between member states' armed forces.

Today, the CSTO comprises six states: Armenia, Belarus, Kazakhstan, Kyrgyzstan, Russia, and Tajikistan. Its geographical focus extends across Eastern Europe and Central Asia, with Russia serving as its principal military power. The organization provides a framework for coordinating the security policies of its members, conducting joint military activities, and responding to shared regional threats.

The CSTO’s institutional development has transformed the original treaty into a more structured security organization, combining collective-defence commitments with broader mechanisms for military cooperation and regional security. There is a possibility, however, that the organization has managed to achieve more in terms of joint military exercises than in actual collective defense.

The CSTO maintains several collective military formations, including the Collective Rapid Reaction Forces, the Collective Rapid Deployment Forces of the Central Asian region, and Collective Peacekeeping Forces. Their preparation involves not only combat units but also intelligence, logistics, command, and specialized chemical, biological, radiological and nuclear (CBRN) defence and medical support. In 2025, the organization conducted 61 joint training activities, while its 2026 programme included 60 planned activities, including eight command-and-staff and specialized exercises. Russia remains the organization's principal military power, but these formations are designed to coordinate contingents from several member states. The main challenge is therefore not simply the availability of national forces, but their ability to operate together under a common command structure.

Recent exercises provide a clearer picture of these capabilities. In September 2026, the Rubezh-2026 exercise in Kazakhstan involved approximately 1,500 servicemen and more than 300 units of military and specialized equipment, including 115 UAVs. Contingents from Kazakhstan, Kyrgyzstan, Russia, and Tajikistan practiced responding to a simulated incursion in which an opposing force had seized border territory and several settlements. The scenario included reconnaissance, blocking and eliminating armed groups, restoring border control, evacuating civilians, and conducting assaults with support from aviation and unmanned systems. These activities demonstrate that CSTO exercises are increasingly incorporating different capabilities into coordinated operations rather than focusing exclusively on conventional ground combat. However, the exercise demonstrates the tasks practiced, not the effectiveness of these forces in an actual conflict.

A similar direction was evident during the Vzaimodeystviye-2026, Poisk-2026, and Echelon-2026 exercises in Russia. Approximately 2,000 servicemen and 350 units of military and specialized equipment participated. The exercises covered different aspects of a joint operation, including reconnaissance, the destruction of enemy positions, logistics, and the coordination of collective forces. Reconnaissance units employed UAVs, including FPV drones, to identify targets and adjust artillery and aviation strikes. Ground robotic systems were also used, likely in logistics roles. Taken together, these activities indicate that the CSTO is attempting to incorporate lessons from the war in Ukraine into collective training, particularly in reconnaissance, target acquisition, and the employment of unmanned systems.

The organization is also addressing the infrastructure needed to support multinational operations. In May 2026, representatives of member states discussed improvements to communications and information exchange, drawing on Russian experience in Ukraine. The discussions covered modern telecommunications equipment, compatibility between different communications systems, and secure information transmission at the tactical level. The CSTO has additionally announced that it has incorporated protection against UAV attacks into future exercises. These initiatives address two important requirements of contemporary warfare: maintaining coordination between dispersed units and protecting forces and facilities against unmanned threats. Nevertheless, the available sources establish that these issues are receiving attention, not that the organization has already achieved effective interoperability or comprehensive counter-drone protection.

Beyond conventional military operations, the CSTO conducts exercises addressing biological threats and peacekeeping. A June 2026 exercise in Saratov involved more than 100 specialists practicing information exchange, operational logistics, and biological-risk assessment during a simulated outbreak of a dangerous infection. The organization reported that its member states possessed more than 100 mobile laboratories capable of conducting up to 1,000 tests per day each. Meanwhile, proposals to establish joint cyber-response mechanisms and elevate the status of the CSTO's emergency-management coordination body indicate an interest in expanding cooperation into additional security areas. These proposals should not be confused with fully implemented capabilities, but the biological-threat exercise demonstrates that at least some specialized collective mechanisms are already being trained and equipped.

The CSTO's effectiveness depends on the political interests of its members. In January 2022, it deployed forces to Kazakhstan following President Kassym-Jomart Tokayev's request, demonstrating its ability to respond rapidly to a member's crisis. However, the unrest stemmed from domestic grievances, and evidence of significant foreign involvement remained unsubstantiated.

The operation demonstrated the organization's capacity for intervention but raised questions about how its mandate is applied.

Russia remains the CSTO's dominant military power. Based on data from 2017, Russia accounted for approximately 95% of member states' combined military spending. Nevertheless, military dependence does not guarantee political support.

This distinction was evident during Ukraine's incursion into Russia's Kursk region in August 2024.

In March 2025, the CSTO Secretary General stated that the organization could consider assisting Russia if European countries deployed troops to Ukraine, although the statement did not establish what such assistance would involve. Nevertheless, Russia did not request assistance under Article 4 of the Collective Security Treaty, and the CSTO mounted no collective response.

The reasons for Moscow's decision remain unclear, but the episode highlighted the limits of collective-defence commitments when Russia itself faces a security challenge.

In Central Asia, the CSTO continues to provide a framework for joint exercises and security cooperation, although members maintain independent foreign-policy priorities. In the South Caucasus, Armenia's disengagement has further weakened the organization's regional role. In August 2026, Prime Minister Nikol Pashinyan declared that Armenia's interest in the CSTO was exhausted and that he did not intend to resume cooperation within the next five years. This indicated that the organization’s guarantees were not attractive enough for one of its members to continue actively pursuing its membership.

The CSTO retains military cooperation mechanisms, but its practical effectiveness is constrained by Russia's dominance, divergent member-state interests, and uncertainty over whether collective-defence commitments would translate into action during a major crisis.

The CSTO remains a functioning framework for military cooperation, but its capabilities are primarily demonstrated through joint exercises, coordination, and preparations for regional crises rather than collective action in major conflicts. Its efforts to improve communications, counter UAV threats, and adapt to modern warfare indicate an awareness of emerging military requirements. However, the gap between these plans and demonstrated operational effectiveness remains unclear.

The organization's future will depend on its ability to maintain member-state confidence and turn military cooperation into credible security guarantees. While the CSTO is likely to retain relevance in Central Asia, Russia's dominance, divergent national interests, and Armenia's disengagement limit its cohesion. It is therefore likely to remain a platform for regional military cooperation, but its ability to function as a unified collective-defence alliance remains uncertain.