When the active phase of Russia’s strategic exercise Zapad (“West”) begins later this week, lasting from 12 to 16 September, governments and analysts will again watch closely. Held every four years, Zapad alternates with the so-called Union Shield drills, whose 2023 iteration was cancelled. Both are designed to test the warfighting capacity of the Russia–Belarus Union State, a special framework of political and military integration. With Russia’s war in Ukraine ongoing, some fear Moscow’s aims could go beyond rehearsing concepts and testing technologies, and instead use deployments as cover for preparing further offensives.

Such concerns are not unfounded: in 2008, 2014, and 2022, major exercises preceded Russia’s interventions in Georgia and Ukraine. Yet, these exercises are not only about combat preparation; they are also instruments of strategic communication, intended to shape perceptions, signal resolve, and strengthen deterrence. The real challenge is reading them correctly. This is where confidence- and security-building measures (CSBMs) may help. They can reinforce deterrence by demonstrating capabilities to observers and clarify the difference between sabre-rattling and genuine threats, but only if all sides share an overlapping interest in stabilizing relations.

Russia’s strategic exercises

Since 2009, Russia has conducted alternating strategic-level exercises to test readiness and train forces at the level of military districts:  Zapad (now split again into the Leningrad and Moscow districts), Kavkaz (Caucasus), Tsentr (Centre) and Vostok (East). They are designed to prepare for potential regional wars against a “peer power”, usually involve tens of thousands of troops from all branches of the armed forces, and sometimes also include domestic security units. All feature complex inter-service operations and extensive troop movements across much of Russian territory.

Among those exercises, Zapad is unique in that it is conducted not only in Russia but also in Belarus, its ally and partner in the Union State. While the active phase of Zapad in autumn is the most visible and publicised, exercise planning begins early, usually the year before. In spring, training and preparation take place within the framework of other exercises, while in summer, Russia assembles and deploys units to the areas designated for the September peak, often under the guise of surprise combat readiness checks.

Zapad’s scenario usually depicts an attack by foreign states with the support of irregular forces aimed at destabilising the Union State and pursuing regime change. Its last iteration, in 2021, for example, envisioned a Western coalition of “Nyaris”, “Pomorie”, and the “Polar Republic” attacking the “Northern Coalition” of Belarus and Russia. The exercise unfolded in two stages: first, a defensive operation to repel the assault, followed by a four-day counteroffensive to reclaim lost ground. Though often ridiculed, such scenarios may also reflect Russian anxieties about mass unrest in Belarus, as seen during the 2020-2021 protests, and prospective Western intervention.

Signals amid the noise

From what is known publicly, the upcoming active phase of Zapad 2025 will resemble earlier iterations in 2021, 2017, and 2013, but on a considerably smaller scale. Lithuanian intelligence, for example, estimates an involvement of no more than 30,000 troops. Of those, only 8,000 will be stationed in Belarus, including 6,000 Belarusian troops. The total will thus be less than half the 2021 numbers. This does not come as a total surprise, however, as Russia’s ongoing war against Ukraine continues to absorb considerable resources.

Faced with such limitations, the kind of information Russia and Belarus have released about Zapad has been purposefully calibrated, turning necessity into design. In May 2025, for example, Belarus claimed that the scale of Zapad would be cut from the originally planned 13,000 by almost half. Simultaneously, officials stated that parts of the exercise would move deeper into Belarusian territory, that is, further away from NATO borders, which was presented as a sign of goodwill and proof of defensive goals.

At the same time, officials have deliberately played the nuclear card to reinforce deterrence. In mid-August, Belarusian Defence Minister Viktor Khrenin announced that Minsk would “together with our Russian colleagues, work through questions of planning the employment” of both “nuclear weapons”, described as an “important element of strategic deterrence”, and the dual-capable, intermediate-range ballistic missile system Oreshnik. Although he stopped short of saying that Oreshnik would actually be employed, the remarks link Zapad directly to the recent deployment of Russian nuclear warheads in Belarus and to plans to base Oreshnik there until the end of the year.

Overall, Zapad has thus also become part of broader nuclear signalling, projecting readiness and strength while exposing anxieties about one’s own vulnerabilities, even as Moskau and Minsk profess peaceful intent and pin blame on NATO. Belarusian officials, for example, have highlighted Poland’s parallel exercise Iron Defender-25, involving more than 30,000 troops, as a source of “concern,” claiming it contributes to “further militarization.” Such rhetoric is neither new nor surprising. But it underscores the central role of diverging perceptions and the need for instruments beyond national intelligence to distinguish between political messaging, deterrence signalling, and genuine preparations for war.

The politics of military transparency

Formally, such an instrument does exist: The Vienna Document on Confidence and Security Building Measures (2011), the main politico-military tool of the Organization for Security and Co-operation in Europe (OSCE). Among other things, it requires the 56 participating states (all but Mongolia) to notify each other at least 42 days in advance of large-scale exercises exceeding certain thresholds. For example, states must be notified if exercises involve at least 9,000 troops, and once they reach 13,000, states are required to invite observers.

However, these provisions only apply to land formations under a “single operational command,” allowing governments to structure exercises in ways to evade transparency. In the past, Russia has exploited such loopholes by breaking large-scale exercises into smaller ones and conducting surprise combat readiness inspections, which are exempt from such regulations. Since the large-scale invasion of Ukraine in 2022, however, Russia has stopped implementing the Vienna Document altogether, halting annual exchanges of military information, as well as inspections and evaluations of units and designated areas.

By contrast, Major-General Valery Ravenko, Head of the Department of International Military Cooperation at the Belarusian Ministry of Defence, said Belarus has notified all participating states about Zapad 2025 and invited observers. Unlike Russia, Belarus has shown a consistent independent interest in CSBMs in recent years. It remains a party to the Open Skies Treaty, which Russia left in 2021, has declared its readiness to open its territory for on-site verification,and continues to request Vienna Document inspection visits in NATO states. Most recently, Belarus proposed to its neighbours a regional CSBM involving information exchange and mutual inspections to a depth of 80 kilometres on both sides of the respective borders.

The changing role of CSBMs

However, these activities and proposals are a double-edged sword amid ongoing combat in Ukraine. While states usually welcome transparency from adversaries, in low-trust environments, they are reluctant to share sensitive data without clear security benefits. Moreover, given its growing dependence on Moscow and its indirect involvement in the war, Belarus’ continued CSBM activities are understandably taken with a large grain of salt. Despite these challenges, CSBMs could still help manage Europe’s growing divide, provided all sides prioritise stability over further destabilisation.

Inviting observers to major exercises, for example, can bolster deterrence by showcasing capabilities and providing another source of information to cross check insights collected by intelligence. However, such practice will only be effective in terms of confidence-building if observers can see full-scale combat activities rather than small, staged segments or given short briefings for military attachés. New tools such as drones could improve monitoring further, but their use would require clear rules of engagement to ensure operational security and careful testing. Because such preparatory work takes considerable time, it should begin now, first at the national level and then among allies, to be ready once political conditions allow.

Finally, CSBMs can only generate additional confidence in peaceful intentions if non-compliance is treated as a signal of political intent that has clear consequences. This has not always been the case in the past, because CSBMs have been treated as a fair-weather instrument, based on misplaced trust in the other side. It has also been the result of insufficient information flows and institutional linkages between different parts of governments, including intelligence and arms control, as well as between policy-makers and practitioners. Improving these mechanisms will help ensure that CSBMs can once again become credible tools for managing confrontation, rather than empty rituals.

The European Leadership Network itself as an institution holds no formal policy positions. The opinions articulated above represent the views of the authors rather than the European Leadership Network or its members. The ELN aims to encourage debates that will help develop Europe’s capacity to address the pressing foreign, defence, and security policy challenges of our time, to further its charitable purposes.

Image: Alamy, Russian Government