Poland as the Leader of NATO’s Eastern Flank and Initiator of the Three Seas Initiative
In recent years, Poland has established itself as a key player in NATO's eastern wing and one of the main initiators of regional cooperation in Central and Eastern Europe. Warsaw makes no secret of its ambition to play a leading role not only in the military, but also in the political and infrastructural spheres, as evidenced by its involvement in both the Three Seas Initiative and the Bucharest Nine (B9) format. The latter was created in response to the growing threat from Russia and has become an important platform for coordination between allies on the eastern flank of the Alliance.
In his inaugural speech, newly elected Polish President Andrzej Nawrocki proposed that the Bucharest Nine be expanded in the long term to include Finland and Sweden—two countries that have recently become NATO members and whose geographical location and military potential could significantly strengthen the region's defense capabilities. According to him, this step would form the "Bucharest Eleven," functioning as the "immune system" of NATO's entire eastern flank.
Poland as the leader of NATO's eastern flank
Since the annexation of Crimea in 2014 and the outbreak of war in Donbas, Poland has become one of the most active members of the North Atlantic Alliance in terms of security on the eastern border. Warsaw has long warned of the risks posed by Russian policy and is among the countries that consistently advocate strengthening the presence of allied troops on their territory and in neighboring states. Poland's efforts culminated in 2015 with the creation of the Bucharest Nine (B9), an initiative created jointly with Romania that brings together NATO's eastern flank countries from the Baltic to the Balkans. The B9 aims to coordinate the positions of member countries on security threats, present a unified voice within NATO, and strengthen the military presence of allies in the region. Poland plays a leading role in this platform and is one of its main organizers, thanks to its geopolitical position, military capacity, and political weight within the Alliance.
Poland's importance is further underscored by its active role in the Three Seas Initiative, which aims to connect the countries of Central and Eastern Europe through investments in transport and energy infrastructure. This initiative not only strengthens the region’s resilience to external pressures but also complements the security dimension focused on by the Bucharest Nine. Poland thus acts as a key player capable of combining the military and political-economic dimensions of regional cooperation.
President Nawrocki and his vision for the expansion of the B9
In his inaugural speech, President Andrzej Nawrocki emphasized that Poland must continue to play a leading role in shaping the security architecture of Eastern Europe. It was in this context that he presented the idea of expanding the Bucharest Nine to include new Alliance members—Finland and Sweden. "My dream is for the Bucharest Nine to become the Bucharest Eleven in the future, expanded to include the Nordic countries," Nawrocki said, describing this format as the "immune system" of NATO's eastern flank. According to the president, the involvement of both Scandinavian countries would strengthen the cohesion of the entire Alliance and at the same time create space for closer cooperation between states that share concerns about Russian aggression. Nawrocki pointed out that Finland and Sweden bring not only their experience and geographical advantages to NATO, but also significant military and technological potential. In his vision, an expanded B9 could become not only a political forum but also a practical tool for coordinating military plans, improving infrastructure, and responding jointly to crisis situations. The speech thus indicated that Poland wants to take advantage of the moment after the accession of both Nordic countries to NATO to strengthen its role as a regional leader and expand the framework that already represents an important pillar of the Alliance's internal cohesion.
Why Finland and Sweden?
The inclusion of Finland and Sweden in the Bucharest Nine format would not only be a symbolic step, but also a strategic strengthening of the entire Alliance. In recent years, both countries have decided to end their long-standing policy of neutrality and join NATO in response to Russian aggression against Ukraine. Their accession to the B9 would thus logically expand the scope of coordination to include states that share immediate concerns about Russian expansion. With its more than 1,300-kilometer border with Russia, Finland is one of the most important allies in the northern part of the eastern flank. Helsinki not only has a well-trained army and a strong defense doctrine (total defense) based on compulsory military service, but also an extensive reserve force that can be quickly mobilized in case of threat. Finland's entry into the B9 would provide the entire platform with unique experience in ensuring security in Russia's immediate vicinity.
Sweden, which joined NATO in 2024, is a key ally for NATO due to its geographical location. In particular, control of the island of Gotland in the Baltic Sea is a crucial factor in the defense of the Baltic states and in securing maritime routes in the region. In addition, Stockholm has modernized its armed forces and a developed defense industry that can support joint Alliance projects. Both countries are already involved in infrastructure projects of strategic importance to NATO, such as the development of the Rail Baltica railway network, which will enable faster movement of troops and equipment between northern and central Europe. Their integration into the B9 could therefore strengthen not only the military but also the logistics and political aspects of the entire eastern flank of the Alliance.
Geopolitical challenges of such an expansion
However, these benefits are accompanied by a number of challenges. The greatest weakness of the current B9 is the differing attitudes of member states towards Russia, with Hungary in particular known for its reluctance to strengthen military structures and sanctions. The expansion to include the Nordic countries would further highlight these differences and could complicate the achievement of consensus. Another question is the interest of Finland and Sweden themselves. Although both countries share concerns about Russian aggression, they also focus their security policy on the North Atlantic and the Arctic region, which may limit their involvement in a predominantly Central European format. Last but not least, the internal dynamics of the group would change. Poland, which today plays a leading role alongside Romania, would have to reckon with the fact that, after the accession of Helsinki and Stockholm, it would have to share this position with other strong partners.
Overall, it can be said that the expansion of the B9 could significantly strengthen the region's defense capabilities and increase the importance of this format within the Alliance as a whole. At the same time, however, it would require careful negotiation and the ability to reconcile different national interests so that the potential Bucharest Eleven does not become merely a formal platform with no real influence.
The Three Seas Initiative in Poland's broader strategy
The idea of expanding the Bucharest Nine fits into Poland's broader strategy, which has long sought to position itself as a leader in regional cooperation in Central and Eastern Europe. In 2015, Warsaw was already at the forefront of the Three Seas Initiative, which aims to strengthen economic, infrastructure, and energy links between countries bordering the Baltic, Black, and Adriatic Seas. This project has not only an economic dimension, but also a clear security context: it creates a basis for greater resilience of the region to external pressures and complements military cooperation within NATO.
For Poland, the Three Seas Initiative is a tool for uniting the countries of Central and Eastern Europe into a cohesive whole that will be able to counter Russian influence and balance power interests within the European Union. The expansion of the B9 to include Finland and Sweden would further support this strategy, as it would symbolically and practically connect Central Europe with the northern part of the continent. Warsaw would thus become not only the leader of NATO's eastern wing, but also a key coordinator of cooperation that extends beyond the traditional boundaries of the region.
