Zapad-25: Comprehensive Details of the Russia-Belarus Military Exercise

Zapad-25 is a major joint strategic military exercise between Russia and Belarus scheduled for mid-September 2025, marking the first large-scale Russia-Belarus military drill since the 2021 exercises that preceded Russia’s full-scale invasion of Ukraine.

Exercise Overview and Timeline

The exercise is set to take place from September 12-16, 2025, representing the main stage of joint military training between Russian and Belarusian forces for 2025. Planning for the exercise began in October 2024, and as of August 6, 2025, the first trainloads of Russian military personnel and equipment have already arrived in Belarus.

The Zapad (meaning “West” in Russian) exercise series has been conducted biennially since 2009 under an agreement between the two countries, alternating between Russian and Belarusian territory every four years. Notably, no Zapad exercise was held in 2023, reportedly due to Russia’s resource constraints from the ongoing war in Ukraine.

Troop Numbers and Scale

Official sources indicate that over 13,000 troops will participate in Zapad-25. However, Western intelligence estimates suggest the actual numbers could be significantly higher:

• NATO estimates project 100,000 to 150,000 troops may ultimately be involved

• Latvian military officials estimate between 100,000-150,000 personnel

• Ukrainian President Volodymyr Zelensky warned in February that Russia planned to deploy up to 150,000 troops (equivalent to 15 divisions) to Belarus

Belarus announced in May 2025 that it would reduce the exercise parameters by nearly half compared to the originally planned 13,000 troops, bringing participation down to approximately 7,000-8,000 forces on Belarusian territory. This reduction was officially described as an effort to ease regional tensions.

Training Locations and Scope

The exercises will take place across multiple training grounds in both countries. In Belarus, the primary locations include established military training facilities, with Belarus announcing that core maneuvers would be moved deeper inland, away from western borders with NATO countries.

According to Belarusian officials, the exercises aim to practice “new forms and methods of applying ground units after analysing the latest modern military conflicts”. The drills are described as testing joint defensive and offensive operations, improving military cooperation, and enhancing readiness for various security scenarios.

Western Concerns and NATO Response

Security Implications

Western officials and military analysts view Zapad-25 with significant concern, particularly given the historical precedent of the 2021 exercises. The Zapad-2021 drills, involving approximately 200,000 troops, directly preceded Russia’s February 2022 invasion of Ukraine, with some Russian forces remaining in Belarus after the exercises and subsequently participating in the assault on northern Ukraine.

Key concerns include:

• Potential threat to the Suwałki Corridor: The narrow 65-kilometre strip of land connecting Poland and Lithuania, which represents NATO’s only land link to the Baltic states

• Simulated attacks on Baltic states and Poland: Previous Zapad exercises have included scenarios rehearsing invasions of these NATO territories

• Cover for actual military buildup: Fear that exercises could mask preparations for genuine military escalation

NATO and Allied Responses

Several NATO countries have taken concrete steps in response to Zapad-25:

• Germany deployed five Eurofighter jets and 150 personnel to Poland in early August 2025, with operations beginning from an airbase east of Warsaw

• Poland is planning its own large-scale military exercises in response, described as “proportional to the scale of Russian-Belarusian troop movements”

• Lithuania has increased intelligence monitoring and is participating in NATO’s enhanced air policing missions

NATO Secretary General Mark Rutte has stated that while the alliance remains vigilant, he does not consider a Russian attack on NATO after Zapad-25 to be a realistic immediate threat.

International Oversight and Transparency

OSCE Obligations

Under the 2011 OSCE Vienna Document, military exercises involving more than 13,000 troops require mandatory international observation, while those with 9,000+ troops require prior notification. Belarus has announced its intention to notify OSCE member states and invite international observers, despite the reduced troop numbers falling below the mandatory thresholds.

However, there remains uncertainty about which countries will be invited as observers, with Belarusian officials indicating they are “formulating their position” on invitations to OSCE member states.

Hybrid Threats

EU officials, led by High Representative Kaja Kallas, have warned of increased risks of hybrid attacks during the exercise period, including:

• Cyberattacks targeting EU infrastructure

• Disinformation campaigns

• Sabotage operations

The EU has activated its Rapid Alert System and EUvsDisinfo platform to counter potential information manipulation during the exercise period.

Regional Security Context

Zapad-25 occurs against a backdrop of heightened tensions between Russia and the West, with the exercise representing part of Russia’s broader military posture toward NATO. The exercise coincides with:

• Ongoing Russian military buildup along NATO’s eastern borders

• Increased hybrid warfare activities across Europe

• Russia’s continued war in Ukraine, now in its fourth year

Baltic and Polish officials emphasise that while immediate attack risks may be limited due to Russia’s commitments in Ukraine, the exercises represent a longer-term threat to regional stability and serve as rehearsals for potential future conflicts with NATO.

The exercise thus represents both an immediate security concern and a broader indicator of Russia’s strategic intentions toward the Euro-Atlantic security architecture, requiring continued vigilance and coordinated response from NATO allies.