Lublin, a city in southeast Poland, is notable as the site where, in 1569, the rulers of Poland and Lithuania (which then included large parts of present-day Ukraine) signed a pact to unite the two countries into a single state to better withstand aggression from Russia. Four and a half centuries on, the city continues playing a role in connecting these three countries as home to the headquarters of the Lithuanian-Polish-Ukrainian Brigade, or “Trilateral Brigade” in members’ own parlance. The brigade’s headquarters is staffed with a mix of soldiers from Lithuania (five), Poland (fifty-eight), and Ukraine (eighteen), and is capable of planning, organizing, commanding, and controlling three associated combat units—one mechanized infantry battalion from each of Lithuania and Poland and a Ukrainian air assault unit—and combat support units (approximately 4,500 total personnel) for international military operations. Despite Russia’s invasion of Ukraine, Ukrainian personnel continue to be assigned to the unit, and the headquarters continues its four main missions of international cooperation: executing and participating in battle staff training, battalion staff officer courses, multinational exercises, and activities of the Joint Military Training Group–Ukraine.

In the shadow of Lublin’s suggestive history, the Trilateral Brigade provides a lens for thinking about flexible options in US and NATO responses to contemporary Russian aggression in Ukraine. This flexibility is especially important in the context of current US doctrine on deterrence in a new phase of great power competition. In August, we traveled to Poland on a DoD Minerva research mission, where we conducted interviews with dozens of military personnel assigned to the Trilateral Brigade. What we found underscores the significance of the organization’s historical roots and highlights the value of this joint military unit acting as a bridge between NATO and Ukraine. While few US and European military personnel are aware of the Trilateral Brigade’s existence, the unit can serve as a template for future security cooperation and facilitate Western efforts in the current Russo-Ukrainian War.

Two Feet in NATO, One Foot Out

The Trilateral Brigade occupies a gray space. While multinational units are not uncommon—the Dutch-German Tank Battalion 414, for instance, was founded in 2016—a joint unit composed of NATO members (Polish and Lithuanian) and non-NATO military personnel (Ukrainian) is obviously rare. This presents both opportunities as well as risks that must be managed in order to take advantage of those opportunities.

NATO is an organization built on the principle of consensus. While this is a critical means of keeping the most successful military alliance in the history of the world together, it also means that even limited activities are difficult when some members are resistant. Here is where an organization like the Trilateral Brigade proves extraordinarily useful. The brigade is a joint training mission, and a lot of activities fall under the category of training—activities that could have direct impacts in the ongoing war in Ukraine, for example. The brigade can therefore play a positive role by enabling Eastern European NATO members who want to lean into what they see as a broad-based confrontation with Russia—what may turn out to be a long conflict of which the war in Ukraine is just the most active and kinetic front—and those further West that might wish to keep the conflict at a distance. These different tolerances for risk point to the range of very real divisions among NATO members and are a foundation of Russia’s strategy of steadily weakening the alliance by exploiting any fissures. The Trilateral Brigade helps bridge these gaps and thus protect against this Russian strategy.

The brigade’s potential contributions to strengthening the defense of NATO’s eastern flank and providing military training in Ukraine is not without difficulties. Chief among these is the risk of escalation, particularly considering the shadow that US and Russian nuclear arsenals cast over the conflict. This concern is real, given the realities of opposed strategic aims: The United States and other NATO members strive to limit conflict to Ukraine’s territory while helping Ukraine’s armed forces inflict enough pain on Russian forces to compel retreat and to deter future aggression. Russia’s leadership seeks to compel the United States and others to stop supporting Ukraine’s armed forces.

Ultimately, the key to managing this risk while also pursuing strategic goals of supporting Ukraine is balance, and the Trilateral Brigade provides additional important options. Assistance managed through the Trilateral Brigade’s decentralized structure is more difficult to target than staging areas and lines of communication associated with assistance to Ukraine. Its functional advantage lies in its capacity to coordinate planning and flows of material resources across a wide territory, and thus may not come with the same risks of escalation as other forward-leaning operations.

Perhaps most fundamentally, the brigade’s unique organization and membership, partly NATO and partly not, should widen our collective perspective on the ways to deliver security force assistance. It leverages an alignment of strategic interests among a subset of NATO members to generate the close coordination between assistance providers and recipients needed for effective security force assistance. With the American strategic vacation over, the United States and its allies and partners must learn from security assistance mistakes with Afghanistan, and forge refined ways of providing military aid that improves Ukrainian military capabilities in a sustainable fashion.

The Trilateral Brigade’s Comparative Advantage

Lublin’s regional and historical importance as the center of the old Polish-Lithuanian Commonwealth are cited as a “factor in the emergence of Ukrainian national consciousness.” Beyond these deep historical ties, official discourse in all three countries involved in the Trilateral Brigade define their identities in terms of repression and resistance during Soviet rule. Shortly after the breakup of the Soviet Union in 1991, Lithuania, Poland, and Ukraine began codifying relationships for military “training-operational cooperation.” Within this identification of shared strategic interests, cooperation among members of the armed forces of these countries began to establish a shared cultural frame for planning and executing operations, a key element in motivating efficient application of military resources and effort.

Formal cooperation between the three militaries began in 1997 with the Lithuanian-Polish Battalion, followed by the establishment of the Polish-Ukrainian Battalion in 1998. Between 2000 and 2010, personnel from the Polish-Ukrainian Battalion (reinforced with thirty Lithuanian troops) were deployed to Kosovo to participate in NATO-led peacekeeping operations. Additionally, Polish and Ukrainian soldiers deployed to Iraq (2003–2005) as part of the Multinational Centre-South Division, which included two Lithuanian infantry companies and logistics personnel. Individually, all three countries contributed forces to support US and NATO missions in Afghanistan (2001–2021) as part of broader goals of improving strategic partnerships with the United States, European Union, and NATO. Personnel from all three countries became familiar with one another as they built personal networks and shared information.

Lithuanian and Polish relationships with Ukraine came to a pause in 2010 when Viktor Yanukovych assumed Ukraine’s presidency, which strained many ties to the US and neighboring NATO countries. Cooperation stagnated until 2014, when Russia annexed Crimea and secretly invaded to initiate a separatist revolt in Ukraine’s eastern Donbas region. After pro-Western leaders returned to power in Kyiv in the wake of the Maidan Revolution, the Trilateral Brigade was formed in late 2014. The brigade achieved operational capability and combat readiness by 2017, as demonstrated by successfully executing its first multinational exercise in December of 2016. This was followed by further symbolic integration as the Trilateral Brigade chose their patron: Grand Hetman Konstanty Iwanowicz Ostrogski. The symbolism was significant: Ostrogski was “the three nations’ hero who successfully led campaigns against the Tatars and Muscovians,” with the greatest unifying victory occurring against Vasili III of Russia in 1514.

In 2020, given deepening defense ties, increased political coordination between Lithuania, Poland, and Ukraine followed. This took the form of the “Lublin Triangle,” an interregional cooperative body with one of its aims being to “coordinate actions to protect international law in the context of Russia’s ongoing aggression against Ukraine both in tripartite coordination and in international organizations.” This was not the first time such a cooperative organization was formed in the region. For instance, GUAM (Georgie, Ukraine, Azerbaijan, Moldova) was formed in 1997 for “quadrilateral cooperation for strengthening stability and security in Europe based on respect for the principles of national sovereignty, territorial integrity, inviolability of state borders, democracy, the supremacy of law and human rights.”

With these examples of growing collaboration between former Soviet and Eastern Bloc states, the United States and NATO should view the proliferation of such organizations as an opportunity to leverage personal and organizational connections, partnerships, and relationships in a way that strengthens defense institution building and the way security assistance is delivered and received.

One caveat is that highly motivated Trilateral Brigade members and their governments may have higher risk acceptance thresholds than the United States and some other NATO country planners; this brings the discussion back to the fundamental concern over escalation described earlier. During our interviews in Poland, we regularly encountered dismissive attitudes toward the risks of Russo-Ukraine War escalation in interactions with the brigade’s personnel and various other members of the three countries’ armed forces. While there is significant alignment of partners’ strategic aims, coupled with significant capabilities, differing assessments of risk pose the possibility that recipients of assistance will use resources in aggressive and provocative ways that are not to Washington’s tastes and would concern NATO partners that do not share experiences of Soviet rule.

Leveraging the Trilateral Brigade in Competition

As the war in Ukraine grinds on, the United States will seek to exploit the opportunity to weaken and undermine Russia in the context of a grand strategy that views Russia as a declining power—though one that happens to possess about six thousand nuclear weapons—and China as a growing, revisionist, flexing regional hegemon. Helping Russia fail militarily in the Eurasian geopolitical context is not only vital for European security, but also for US and NATO plans to pivot resources, military forces, and strategic thinking toward Asia to contain China’s growing power.

There are three important policy implications of having a non-NATO member like Ukraine codifying relationships with NATO members through a joint security organization like the Trilateral Brigade.

First, the greatest value of the Trilateral Brigade lies in its ability to operate outside of the figurative NATO umbrella while minimizing risks of territorial escalation, as the brigade’s commander told our research team. In practical terms, it means that while the United States and NATO have to be comparatively more legalistic and bureaucratic in training, assistance, advising, and equipping Ukraine, the established regional cooperation of the Trilateral Brigade enables interoperability and long-term relationships between these countries in a way that is difficult for the average US or NATO military unit to achieve. Moreover, such an established regional security organization can enable informal coordination and the sharing of information. Per our interviews, the Trilateral Brigade facilitates numerous activities between Ukrainian forces and NATO, such as collecting lessons learned from open sources and personnel involved in the war against Russia. Such data informs military exercises and makes training more realistic between US, European, and Ukrainian personnel.

Second, given growing discussions about Ukraine acquiring 48 to 128 American F-16s, the precedent of a Trilateral Brigade suggests that similar cooperative activities could take place between NATO members and Ukraine. For example, Poland has forty-eight F-16s and Romania has seventeen (plus thirty-two more being acquired this year). This suggests an opportunity to form a bilateral Polish-Ukrainian air squadron or a trilateral Polish-Romanian-Ukrainian air squadron. An operational template of sorts already exists with the Heavy Airlift Wing in Hungary, where twelve countries (the United States, nine other NATO members, and Sweden and Finland) jointly operate three C-17s. Employing joint air force units would be a bridging function for the Ukrainian military, enabling Ukrainian pilots and associated support personnel to learn best airpower practices from their neighbors. This would prevent the Faberge Egg military problem that typically occurs when American advisors are not around to monitor a partner force operating an expensive and complicated weapon system like the F-16 (Iraq, for example, struggles to operate its fleet of F-16s). The significance of this was highlighted while interviewing a Polish fighter pilot, who explained a “mentality change on every level” was needed when Poland established its first F-16 squadron at Poznań air base in 2006. He admitted numerous struggles in the transition away from Soviet-era aircraft and standards for logistics, maintenance, and airfield support. Finally, growing regional cooperation between air forces could possibly accelerate timelines for Ukrainians to be able to employ F-16s more skillfully in combat operations once they are deemed capable of operating independently out of air bases in Ukraine (likely two to three years).

Third, given the deep ties the Trilateral Brigade is fostering between Lithuanian, Polish, and Ukrainian forces, there is an opportunity for NATO and the United States to further enhance the relationship between Western militaries and Ukrainian security forces. For instance, the Lithuanian-Polish-Ukrainian Brigade’s leadership mentioned how beneficial the US National Guard State Partnership Program was in facilitating training sessions with National Guard units of California, Illinois, and Pennsylvania, which helped them refine training courses on the Military Decision-Making Process. Future engagements with the Trilateral Brigade could include the Canadian military teaching the Operational Planning Process and the British military instructing their 7 Questions combat estimate method. Finally, with the Trilateral Brigade having submitted a plan of training ten thousand Ukrainian infantry by 2023, this presents an opportunity to assign officers and noncommissioned officers from the United States and NATO to act as liaison officers in advising, developing, and facilitating such activities. This would further enhance and improve the combat power and professionalization of Ukrainian forces.

Leaders from the United States and other NATO members continually consider the ladder of escalation—in terms of what lethal and nonlethal aid to provide next to Ukraine—and how Russia might respond. Numerous fundamental realities shape the contours of the overall war, however. Ukraine cannot fight the war with Russia to total victory, for instance, since Russia would never let Ukrainian forces march on Moscow without a nuclear strike. This is precisely why the Trilateral Brigade offers such a significant opportunity. It presents an alternative capability to NATO, a means of indirectly hurting Russia via the training of Ukrainian troops and other coordination activities that enable Ukrainian combat power. It is also a powerful proof of concept, and a strong argument for NATO leadership to encourage the forming of similar joint units with non-NATO members (e.g., Moldova, Georgia, etc.) that also view Russia as a threat to their security. Such collaboration lays the foundation for future security cooperation to improve interoperability capabilities that might be needed in a future conflict.

Lieutenant Colonel Jahara “FRANKY” Matisek, PhD, (@JaharaMatisek) is the fellowship director for the Irregular Warfare Initiative and US DoD Minerva researcher that will be a military professor at the US Naval War College beginning in October 2022. A 2020 Bronze Star recipient for his time as the director of operations and commander of the 451st Expeditionary Operations Support Squadron, he is a command pilot that previously served as a senior fellow for the Homeland Defense Institute and associate professor in the Military and Strategic Studies Department at the US Air Force Academy.

Dr. William Reno is professor and chair of the Political Science Department at Northwestern University. He has conducted fieldwork and interviews in conflict zones across Africa and the Middle East for over thirty years, having authored three books: Corruption and State Politics in Sierra LeoneWarlord Politics and African States, and Warfare in Independent Africa. Dr. Reno has published over one hundred articles in peer-reviewed journals, policy-relevant periodicals, and edited volumes on civil wars, rebels, and military assistance. Finally, he is the principal investigator for the US DoD Minerva-funded program studying how the United States can improve foreign military training.

The views expressed are those of the authors and do not reflect the official position of the United States Military Academy, Department of the Army, Department of the Air Force, or Department of Defense. This article was supported by the Air Force Office of Scientific Research under award number FA9550-20-1-0277.

Image credit: Staff Sgt. Philip Steiner, US Army