Bucharest Nine and the Three Seas Initiative remain unequal to the task

On paper, NATO’s eastern flank, stretching from Norway and Finland in the Arctic to Romania and Bulgaria on the Black Sea, forms a coherent geopolitical frontline in the Alliance’s strategic stand-off with Russia. All these countries, with one quasi-exception, are now members of both NATO and the EU. Only Norway, which borders Russia directly at the top of the Scandinavian peninsula, breaks the pattern somewhat: It’s not technically an EU country although it aligns closely with Brussels and is part of the Single Market.

This remarkable coherence across the fundamental parameters of defence, economic framework, and geography – a compact line of allies briefly interrupted only by the Gulf of Finland and the Suwalki Gap – is of a relatively recent vintage. Finland only joined NATO in 2023 with Sweden. Romania and Bulgaria joined the EU in 2007. The great Flank may be of enormous importance – the future of European security hinges on its sustainability – but as a political-strategic construct it remains underdeveloped and riven with contradictions that sit below its substantial façade. Of most concern is the continuing divide between its two halves.

In the North, the UK-led Joint Expeditionary Force (JEF) nations, from Britain and the Netherlands through Scandinavia to the Baltic countries and Poland, are operating at a far more advanced and deeper level of defence-industrial, political, military and economic cooperation and coordination (including military interoperability). This activity is building up strategic depth and a serious backstop for the frontline states in the area.

The North is particularly stronger militarily: More integrated and thoroughly tested in exercises, including crucially at the command level. It excels in rapid response and maritime/hybrid focus – see for example the Nordic Warden JEF Response Option, quickly activated in 2024 to deal with threats to underwater infrastructure. There is also joint procurement between many of these Nordic countries, for example on naval strike missiles, or a collaborative programme on the Common Armoured Vehicle System. 

Then there are reduced trade barriers, shared supply chains, as well as innovation-sharing to boost European capacity, enabling goals like equipment and personnel interchangeability among navies and deeper integration of high-readiness forces, with the aim of creating a “force of friends” with cultural affinity, standardised procedures. Finally, political relations between most of these countries are deep, with further regional forums such as the Nordic-Baltic Eight helping in that regard. Consultation is permanent, often close, with a shared sense of threats and opportunities, and with a joint understanding of the need for geopolitical solidarity.

Meanwhile, the southern part of the eastern flank, from Slovakia and Hungary to Romania and Bulgaria, with its own wider belt nations located behind the front line, including Czechia, Slovenia and the Balkans, presents a much less compelling picture. History doesn’t help, as many of these countries – most of them ex-Communist – share more in old mutual grievances than in mutual trust. Sure, the Russian threat has given them a common security interest, but individual interests – including, often, political rivalries over primacy in the good graces of Washington and Brussels – sometimes override other concerns.

The two most prominent formats for coordination in this region are Bucharest Nine (B9) – which runs from Bulgaria up to Estonia, stretching a bit into Nordic strategic territory but with its geopolitical weight very much South of the halfway line – and the Three Seas Initiative (3SI) which has a similar membership, with the addition of the likes of Greece and Austria. Alas, neither of them appears as a convincing strategic success delivering meaningful results across the region.

B9 and 3SI have been around for over a decade. Both formed in 2015 in response to Russia’s seizure of Crimea: One as more of a political gathering to “coordinate positions” on security matters – a kind of East European lobby group within NATO; the other as a regional development initiative for Central and Eastern Europe (CEE) – between the Baltic, Adriatic and the Black Sea – with a focus on cross-border infrastructure in transport, energy, and digital sectors along the north-south axis. The US has tended to be supportive of both, principally because the anchor countries of both B9 and 3SI are Poland and Romania, themselves close and dedicated US allies.

But B9 has so far remained a talking shop: Certainly useful, as such formats always are to some extent, but not a grouping whose influence can be clearly linked to any major military or diplomatic outcomes that would not have occurred otherwise. Certainly as regards NATO policy in Eastern Europe, or any other major strategic questions, it is still the big players – especially the US, UK, France, Germany, Poland – who set the agenda.

3SI, on the other hand, is an eminently practical project – but one that delivers just too little too slowly. After ten years of existence, the sum total of actual money committed – not all of it even actually spent – through the 3SI’s investment fund is about €800 million. This is less than impressive for a region of 120 million people across all 3SI’s member states, with a combined GDP of over €3.5 trillion, and with assessed infrastructure investment shortfalls of some €600 billion. These hard cash realities tend to get obscured by the barrage of commentary and PR around the multiplicity of very useful infrastructure projects that are being developed under 3SI; these make for good press and “narratives”. But they are not strategically meaningful at the scale of the region’s requirements or of the geopolitical stakes involved.

All of this is a great shame, as both B9 and 3SI are sound ideas that, if properly implemented and scaled up – in ambition, resources and assertiveness – could transform CEE and therefore bring the two halves of the eastern flank into balance. For now, they have not yet passed the test of geopolitical maturity. In principle, B9 could become a true engine for defence capability for its members, through a virtuous circle of joint procurement and R&D, defence investment, and heightened military interoperability – which is what is needed. 

3SI could, likewise, shift into higher gear – much more joint investment but also wider economic coordination and preferential partnering – and become the basis of a political-economic CEE bloc within the EU. In this way it could come to control the Union itself. Of course, all these will remain but dreams as long as New Europe fails to see the imperative – and opportunity – of acting together with purpose, and carving out its own future on its own terms rather than those set elsewhere. But never say never.