Why expanding the Bucharest 9 format will not add more security to NATO’s Eastern Flank

Press conference of Presidents Karol Nawrocki of Poland and Nicușor Dan of Romania, Warsaw, February 5th, 2026. Photo: Wikimedia

When Romanian President Nicușor Dan and Polish President Karol Nawrocki held their first bilateral summit in Warsaw in early March, the headline ambition was striking: expanding the Bucharest 9 (B9) security cooperation format to include the Nordic countries, potentially transforming it into a B11 or B12. It was a gesture of alliance solidarity at a time when European security architecture is being challenged both by Russian aggression in Ukraine and by United States’ conventional withdrawal. In fact, one of the rationales why Bucharest aims to expand this format is to attract many heads of state to Romania’s capital and make a case for inviting a senior American official at the summit scheduled for later this Spring – aiming for Secretary of State Marco Rubio. This would be aimed at signalling both Eastern Flank unity ahead of the NATO summit in Ankara and America’s continued engagement in the region.

But boldness, initiative, and strategic wisdom are not the same thing. Rather than enlarging a format already struggling with internal contradictions that dilute its relevance, Romania’s president should redirect his country’s diplomatic energy to where it is most urgently needed – the Black Sea.

B9 was founded in 2015 as a Romanian-Polish initiative designed to amplify the Eastern Flank’s voice within NATO. Its rationale was simple: the smaller frontline states needed a platform to coordinate and advocate collectively for a more robust NATO deterrence posture in the face of a revisionist Russia. For a time, it served that purpose adequately. But since Russia’s full-scale invasion of Ukraine in 2022 , the format composed of the nine Eastern Flank countries has been unable to keep pace with the urgency of the moment and produce political consensus. The reason is structural, not circumstantial.

The B9 format suffers from a fundamental issue: its members do not share the same threat perception vis-a-vis Moscow. Hungary and Slovakia, governed by leaders that are openly sympathetic to Russia and depend heavily on its energy, have consistently dissented from the group’s consensus on Ukraine. The Czech Republic’s drift toward right-wing populism under the leadership of Andrej Babis further complicates coordination. The result is a format whose communiques are watered down to accommodate the lowest common denominator, and whose political weight within NATO and the EU is diminishing accordingly. Adding two or three Scandinavian states to this arrangement does not fix the underlying problem – it only further compounds it. More members with different strategic outlooks mean more negotiation, more dilution, less coherence, and less momentum.

The Nordic countries, meanwhile, are already deeply embedded in a format that works: the Nordic-Baltic 8 (NB8). This grouping has distinguished itself precisely because its members share a coherent and urgent threat perception vis-a-vis Russia. NB8 leaders have met many times at the head of state level since the war in Ukraine started and have been among the most vocal and consistent advocates for Ukraine’s territorial integrity. Intragroup coordination has often translated into political commitments. Pulling Nordic states into the B9 orbit risks diluting their effectiveness within NB8 without meaningfully strengthening the B9. It is, in short, a solution in search of a problem.

There is, however, a real problem when it comes to the Eastern Flank of NATO that is not being addressed effectively: the deteriorating security environment in the Black Sea. Following the American withdrawal of troops from the region in October 2025, the south-eastern flank of NATO has become the Alliance’s most vulnerable and least coordinated theatre. Romania sits at the heart of this gap. While the northern flank is increasingly well-organized through B9 and various “minilateral” defence arrangements like the Joint Expeditionary Force and the Baltic Defence Line, the southern arc connecting Romania, Bulgaria, and Turkey remains comparatively shallow in its security cooperation. This is not merely a regional concern. The Black Sea is a strategic corridor with implications for energy supply, grain exports, and the military balance in the broader European theatre.

This is where President Dan’s diplomatic capital should be invested, precisely because Romania’s national security strategy adopted in 2025 highlights the ambition of this country to become a regional leader of South-Eastern Europe. Two trilateral frameworks deserve particular attention. The first is Romania-Bulgaria-Turkey, which has already developed a concrete project together for de-mining the Black Sea. All three countries shape a Black Sea coastline and have a direct stake in the region’s security. Bulgaria, despite its historically cautious posture, has been nudged toward greater NATO engagement by the pressures of the war in Ukraine. Turkey, a complex but indispensable NATO ally, controls the Bosphorus Strait under the Montreux Convention and has demonstrated clear interest in maintaining its strategic relevance in the region by creating a Black Sea maritime security coalition following a settlement in Ukraine. The trilateral between Ankara, Bucharest and Sofia should be expanded to include maritime surveillance, port coordination, joint exercises, and crisis communications protocols that would establish the Black Sea as a zone of active Allied deterrence rather than passive vulnerability.

The second is Romania-Poland-Turkey. This format received less attention but holds significant potential for the regional security framework. Poland and Romania are the two largest frontline states in NATO’s east and both have demonstrated a willingness to invest seriously in defence, being the two largest beneficiaries of loans from the new EU SAFE programme for rearmament. Turkey, on the other hand, has the greatest military in the region, as well as political capital as a middle power. Rather than consuming energy to expand the B9 format, the presidents of these three countries should meet before the NATO summit in Ankara this July to harmonize their vision regarding the future regional security architecture and pool their resources for an effective deterrent against Russia, who has been testing Allied patience through aggressive actions below the threshold of armed conflict.

One has to be aware of the limits of portraying “minilateralism” as a branding exercise. Formats like the B9 derive their value not from their size, but from their coherence and ability to translate political alignment into actionable outcomes. When formats grow beyond the threshold of shared interest, they become talking shops rather than decision-making bodies. The NB8 works because its members are genuinely aligned. The B9 struggles because they are not. Enlargement is not a cure for misalignment – it is an amplifier of it.

There is a subtler political risk lurking beneath the expansion proposal that deserves equal attention: the danger that an enlarged B9 would become an arena for competitive signalling toward Washington rather than a platform for genuine security coordination. In the current transatlantic climate, in which the Trump administration has shown its preference for bilateral deals over multilateral formats, smaller NATO members face strong incentives to use high-profile summits and format announcements as bids for American attention. An expanded B11 or B12 risks accelerating this dynamic, with member states grandstanding for Washington’s favour rather than building the patient infrastructure of regional deterrence. This would further strain the already fragile Eastern Flank’s cohesion along the Visegrad fault line. The Czech Republic, Hungary and Slovakia, which are three members of the B9 with increasingly Ukraine-sceptic foreign policy orientations, could exploit an enlarged and unwieldy format to pursue their own bilateral agendas with the United States, deepening the fractures in the region rather than bridging them. This dynamic would likely match the objective of the United States’ national security strategy to export MAGA ideology to Europe by “building up the healthy nations of Central, Eastern, and Southern Europe” at the expense of European unity. An expanded B9 would not merely be ineffective, but it could actively provide new vectors for the kind of divide-and-rule strategy that Moscow has sought to exploit across Central and Eastern Europe.

Romania, as the host of the Bucharest 9 summit in 2026, has a rare opportunity under President Dan to assert itself as a serious security actor on the Eastern Flank. This will be done not by managing an unwieldy and fractious multilateral forum, but by building durable bilateral and trilateral structures around concrete shared interests. The Black Sea is Romania’s strategic backyard and its most pressing security challenge. Filling the vacuum left by the American withdrawal, strengthening maritime deterrence, and stitching together a functional southern flank coalition comparable to that in the north-east of the continent are objectives that serve Romanian, Allied, and European interests simultaneously.

There will always be political appeal in announcing the expansion of an existing format. It signals ambition, generates headlines, and flatters all parties involved. But in a security environment as demanding as today’s, Romania cannot afford to mistake diplomatic theatre for strategic substance. The Eastern Flank does not need a bigger tent, but better architecture, and the Black Sea is where that architecture must be built.

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Bucharest, Eastern flank, NATO, Nicușor Dan, Poland, Romania