NGRNAnalysis by Consortium for Defence Information
The discussion of security guarantees for Ukraine, combining national forces with foreign military presence after a ceasefire with Russia, parallels similar challenges faced by Eastern European countries.
The estimation of Ukraine’s potential military force structure, based on the models of Poland, Romania, and the Baltic states, follows a comparative modeling approach. This analysis considers national defense structures, foreign troop presence, and defense expenditures across NATO’s Eastern Flank. The study presents several possible models, with the methodology for modeling outlined at the end of the paper.
Ukraine’s potential integration into European security structures requires a comprehensive strategy that balances national defense capabilities with European multinational military support. Drawing from the defense models of Poland, Romania, and the Baltic states, Ukraine could adopt different configurations of ground forces, air power, and multinational troop presence. Each model offers varying degrees of national control, reliance on allies, and financial implications, with scenarios ranging from a strong independent force to a highly integrated security structure.
Instruments of Eastern European Defense Integration
Ukraine can draw valuable lessons from NATO’s Enhanced Forward Presence (eFP) deployments in Poland, Romania, Bulgaria, and the Baltic states. These models emphasize multinational collaboration, strategic positioning, and capacity building to deter aggression and enhance regional security.
NATO’s eFP has established multinational battlegroups across Eastern Europe, each led by a framework nation with contributions from various member states. For example, the U.S. leads Poland’s battlegroup, including forces from the UK, Romania, and Croatia, while Germany leads Lithuania’s battlegroup with troops from the Netherlands, Norway, and Belgium. These units, typically around 1,000 troops, operate on a rotational basis to ensure a continuous presence.
Establishing similar multinational units in Ukraine would enhance interoperability and signal a unified commitment to its defense. Rotating leadership roles among framework nations would foster shared responsibility among European allies.
NATO Force Integration Units (NFIUs) serve as small headquarters facilitating rapid NATO force deployment, coordinating training and exercises, and assisting in logistics planning. They currently operate in Bulgaria, Estonia, Latvia, Lithuania, Poland, and Romania.
Setting up NFIUs in key Ukrainian locations would improve coordination between Ukrainian forces and European allies, ensuring swift responses to potential threats.
Air policing in Eastern Europe is another key component of collective defence. One of the most established air policing efforts is the Baltic Air Policing (BAP) mission, which has been in place since 2004. It protects the airspace of Estonia, Latvia, and Lithuania, countries that lack their own fighter jet fleets. To maintain coverage, NATO deploys fighter jets on a rotational basis, with aircraft stationed at Šiauliai in Lithuania and Ämari in Estonia. At any given time, between four and eight NATO fighters are on duty to provide immediate responses to any airspace violations.
In the Black Sea region, NATO launched an Enhanced Air Policing (eAP) mission in Romania and Bulgaria following Russia’s annexation of Crimea in 2014. This initiative strengthens air defense by deploying NATO aircraft to Mihail Kogălniceanu Air Base in Romania and Graf Ignatievo Air Base in Bulgaria. These bases regularly host four to eight allied fighter jets, providing reinforcement to local air forces and ensuring rapid reaction capabilities.
Poland plays a central role in NATO’s air defense strategy with its own fleet of F-16 and MiG-29 fighters. In addition to national efforts, NATO allies contribute rotational deployments. In 2022, more than 20 NATO aircraft, including F-35s, Typhoons, and Rafales, were stationed at air bases in Łask, Malbork, and Poznań, further bolstering regional security.
In Slovakia and Hungary, NATO’s air policing responsibilities have expanded due to Slovakia’s retirement of its MiG-29s in 2022. Since then, Czech and Polish jets have taken over the task of patrolling Slovak airspace, ensuring uninterrupted security coverage. Meanwhile, Hungary’s Gripen fleet continues to contribute to NATO’s regional air defense cooperation.
At any given time, between 12 and 18 NATO fighter jets are actively deployed in the Baltic and Black Sea regions, maintaining a round-the-clock presence. Over the course of a year, more than 50 NATO aircraft rotate through Eastern European air bases, ensuring a sustained commitment to regional security. Air policing missions frequently intercept unauthorized Russian military aircraft, preventing airspace violations and reinforcing NATO’s deterrence posture.
Eastern European countries have strengthened their defenses through various bilateral and multilateral agreements. Poland and the Baltic States conduct regular joint exercises and intelligence-sharing, while Romania and Bulgaria collaborate on Black Sea security, including joint naval exercises and air policing missions. Poland engages in joint ventures to produce armored vehicles and missile systems, while Romania upgrades its defense infrastructure through international partnerships.
Scenarios for Ukraine’s defense posture in Europe
The Poland Model for Ukraine would mean a Strong national force with limited foreign support/ This model envisions Ukraine as the largest conventional military force in Europe, maintaining a robust national army and air force with moderate NATO support for deterrence and training. Similar to Poland’s approach, a strong domestic military is reinforced by select multinational units.
Ukraine’s armed forces would comprise approximately 450,000 active troops, including modernized armored, mechanized, and artillery brigades. NATO and foreign troop presence would be limited to 15,000–20,000 personnel, focusing on training, rapid reaction, and rotational air policing. The country would heavily invest in air defense, intelligence, surveillance, reconnaissance (ISR), and rapid deployment forces, with NATO-backed missile defense systems and military infrastructure under national control.
Ukraine’s Force Composition Based on Poland’s Model
| Category | Poland (Current) | Ukraine (Modeled) |
| National Army Size | 250,000 troops | 450,000 troops |
| Foreign Troops Present | 11,600 (U.S. + NATO) | 15,000–20,000 (NATO allies) |
| Main Battle Tanks | 1,000+ (Leopard 2, Abrams, K2) | 1,500+ (T-64, T-72, Leopard 2, Western tanks) |
| Infantry Fighting Vehicles | 3,000+ (Rosomak, Bradley, Borsuk) | 4,000+ (BMP-2, Bradley, CV90, AMX-10RC) |
| Combat Aircraft | 96 (F-16s, FA-50s, F-35s) | 120–150 (MiG-29s, Su-27s, F-16s, Mirage 2000, Gripen, Rafale) |
| Foreign NATO Aircraft (Rotational) | 6–12 (F-35s, Typhoons, F-22s) | 12–18 (from Poland, UK, Germany, France) |
| Air Defense Systems | Patriot, NASAMS | Patriot, SAMP/T, NASAMS, IRIS-T |
| NATO Air Policing Hubs | Lask, Malbork, Poznań | Lviv, Kyiv, Mykolaiv, Odesa |
Transitioning to this model would take 5–10 years, requiring extensive procurement and NATO partnership agreements. The estimated annual budget for force modernization, NATO coordination, and air defense upgrades would range between $20–30 billion.
Strategically, Ukraine would become the most capable military force in Europe outside the U.S., maintaining full control over national security strategy while leveraging NATO reinforcement. This approach fosters close coordination with Poland, Romania, and the UK without compromising operational autonomy.
The Romania Model for Ukraine would mean a balanced European-integrated force. This model envisions Ukraine as more deeply embedded within NATO structures, with a significant foreign military presence, including permanent NATO air policing detachments and multinational land forces. It reflects Romania’s defense strategy, where a strong national military coexists with an extensive NATO footprint for regional security.
Ukraine’s armed forces would consist of 350,000 troops, focusing on territorial defense, rapid deployment, and combined air-land operations. NATO presence would include 25,000–30,000 troops, with U.S.-led multinational divisions stationed in western Ukraine. Permanent Quick Reaction Air (QRA) forces would operate from Lviv, Odesa, and Vinnytsia, supporting NATO’s Black Sea Air Policing Mission. The model also envisions extensive NATO missile defense, ISR, and cyber warfare capabilities, alongside naval integration with Romania and Bulgaria for Black Sea defense.
Ukraine’s Force Composition Based on Romania’s Model
| Category | Romania (Current) | Ukraine (Modeled) |
| National Army Size | 80,000 troops | 350,000 troops |
| Foreign Troops Present | 4,700 (France-led NATO) | 25,000–30,000 (UK, France, Poland, Germany) |
| Main Battle Tanks | 350+ (Leopard 2, Abrams) | 1,000+ (T-64, T-72, Leopard 2, Abrams) |
| Combat Aircraft | 30 (F-16s, future F-35s) | 100–120 (Su-27s, F-16s, Mirages, Gripens, Rafales) |
| Foreign NATO Aircraft (Permanent QRA) | F-16s, Typhoons, Rafales | 25–35 NATO aircraft (stationed in Ukraine full-time) |
| NATO Air Policing Hubs | Mihail Kogălniceanu, Câmpia Turzii | Lviv, Odesa, Vinnytsia |
Transitioning to this model would take 8–12 years, requiring NATO consensus and infrastructure development. The estimated annual budget for infrastructure, air defense, and multinational force coordination would range between $25–40 billion.
Strategically, Ukraine would become a key NATO hub for regional defense, integrating heavily into NATO command structures, particularly in air and missile defense. This model enhances deterrence but increases dependence on foreign forces, resembling Romania’s security framework.
The Baltic Model for Ukraine would mean a Europe-reliant defense. This model envisions Ukraine depending primarily on NATO forces for deterrence, similar to the defense structures of Estonia, Latvia, and Lithuania. Under this framework, Ukraine would maintain a compact national military of approximately 200,000 troops, supplemented by a substantial NATO presence of 40,000–50,000 foreign troops and extensive NATO air policing.
Ukraine’s Force Composition Based on Baltic Ratios
| Category | Baltics (Combined) | Ukraine (Modeled) |
| National Army Size | 25,000 troops | 200,000 troops |
| Foreign Troops Present | 9,500 (NATO eFP forces) | 40,000–50,000 (UK, France, Poland, Germany) |
| Foreign NATO Aircraft | 12–16 (Germany, UK, Canada) | 50–60 NATO aircraft (permanent QRA in Ukraine) |
| NATO Air Policing Hubs | Šiauliai, Ämari, Lielvārde | Lviv, Kyiv, Odesa, Mykolaiv |
The transition to this model would take an estimated 5–7 years, contingent on full NATO commitment. With NATO covering a substantial share of security costs, the projected annual defense budget for Ukraine under this framework would range between $15–25 billion.
Strategically, this model would fully integrate Ukraine into NATO’s defense structure, reinforcing deterrence but at the cost of some national autonomy. The presence of major NATO air bases within Ukraine would serve as a strong deterrent against Russian incursions. While financially sustainable due to NATO support, this approach would increase Ukraine’s reliance on alliance decision-making in security matters.
A Hybrid Approach for Ukraine would mean a balanced alternative that could involve elements of both the Poland and Romania models, allowing Ukraine to maintain a robust national military while leveraging NATO reinforcements for air and missile defense. With an estimated annual cost of $20–35 billion, this approach would provide a balance between deterrence and operational independence, ensuring security while maintaining flexibility in strategic decision-making.
The methodology used for modeling
As Ukraine defines its security trajectory, its force structure must align with strategic priorities. The evaluation framework balances military size, foreign troop presence, air defense requirements, and budgetary constraints.
The scale of Ukraine’s military forces must be adapted to its geographical expanse, security threats, and population size. Poland, Romania, and the Baltic states each offer distinct models of military organization and international cooperation.
Factors for scaling for the national force of Ukraine
| Factor | Poland Model | Romania Model | Baltic Model | Ukraine Estimate |
| Landmass | 3.3× Poland | 2× Romania | 30× Estonia | Adjusted force size |
| Threat Level | Requires twice Poland’s force due to active threats | Needs NATO reinforcement in Black Sea region | Relies on NATO for deterrence | Requires self-sustaining force |
| Population | 38M, 250K military (0.65%) | 19M, 80K military (0.42%) | 6M, 25K military (0.42%) | ~38M, ~450K military (1.2%) |
Ukraine’s security calculations must include the potential presence of European forces on its territory. Analyzing similar deployments in Eastern Europe provides a benchmark for estimating realistic force sizes.
Factors for scaling for the European ground force presence in Ukraine
| Country | National Military Force | Foreign Troops | % of Force |
| Poland | 250,000 | 11,600 (U.S., UK, NATO) | ~4.5% |
| Romania | 80,000 | 4,700 (France, U.S.) | ~6.0% |
| Baltics | 36,000 | 9,500 (Germany, UK, Canada, U.S.) | ~25% |
The presence of foreign troops in Ukraine would depend on the defense model it adopts. A self-reliant approach, similar to Poland, would limit foreign forces to under five percent of the total military, with an estimated 15,000 to 20,000 troops stationed in the country. A more integrated structure, following Romania’s example, would involve a larger NATO presence, with 25,000 to 30,000 troops permanently deployed. In contrast, a heavily NATO-dependent model, resembling the Baltic states, could see as many as 40,000 to 50,000 foreign troops, accounting for approximately a quarter of Ukraine’s total force.
The role of air power is central to Ukraine’s defense, particularly in maintaining air superiority and deterrence.
Factors for scaling the European air policing in Ukraine
| Country | National Fighters | Allies’ Aircraft | Air Policing Strategy |
| Poland | 96 (F-16, FA-50, F-35s) | 6–12 rotational | Self-reliant with NATO support |
| Romania | 30 (F-16, future F-35s) | 25–35 permanent QRA | Integrated with NATO forces |
| Baltics | No national force | 50–60 permanent NATO jets | Fully NATO-dependent |
Ukraine’s air defense strategy could take different forms depending on the chosen level of European defense integration. A self-sufficient model would involve maintaining a fleet of 120 to 150 fighter jets while hosting a limited rotational presence of 12 to 18 allies’ aircraft. A more integrated approach, aligned with European quick reaction force strategy, would see Ukraine operating between 100 and 120 national fighters alongside a permanent deployment of 25 to 35 allies’ jets. Alternatively, a model heavily reliant on European force for air defense would involve a smaller national fleet of 80 to 100 jets, with 50 to 60 allies’aircraft permanently assigned to air policing missions.
Sustaining an advanced military requires financial planning that aligns with economic realities. Eastern European countries provide useful benchmarks for defense spending.
Balancing Costs and Sustainability
| Country | Defense Budget | % of GDP | Spending Per Soldier |
| Poland | $37B | >4.0% | $148K |
| Romania | $8.5B | ~2.5% | $106K |
| Baltics | $4.5B | >2.5% | $180K |
Ukraine’s defense spending would vary depending on the chosen model. Under the Poland model, expenditures would range between $50 and $60 billion annually, accounting for approximately 4 to 5 percent of GDP. A structure similar to Romania’s would require a budget of $35 to $45 billion per year, representing 3 to 4 percent of GDP. A more NATO-dependent approach, following the Baltic model, would reduce costs to $20 to $30 billion annually, or about 2.5 to 3 percent of GDP, with a significant portion covered by NATO contributions.
Ukraine’s current wartime defense budget suggests the Poland Model is sustainable in the short term, while long-term feasibility hinges on Europe’s financial commitment.