The Baltic Sea is now almost entirely a “NATO lake”. Apart from Russia's Kaliningrad Oblast and a small coastal strip around St Petersburg, virtually every inch of its shoreline belongs to the Alliance. This is not just a map change; it is a game-changer for daily life and strategic thinking.
When former Finnish President Sauli Niinistö said, “You caused this. Look in the mirror” in 2022, he really hit the nail on the head. That simple statement perfectly sums up the massive shake-up in European security. Putin's full-scale invasion of Ukraine was meant to fracture the Alliance and stop NATO from growing. Instead, he accidentally helped us build a stronger, united front – a truly formidable “double-sized wall” against aggression. It is now clear that the centre of European security has shifted to the North-East. Within the Baltic Sea region, there is now clear political resolve and robust military means for deterrence. This transformation, driven by Finland and Sweden's accession to NATO, has fundamentally reshaped the Nordic-Baltic security landscape and established a vital new front line for European defence
For us here in Estonia, Latvia and Lithuania, the weight of this change feels immediate and immense. Our security has always been a primary concern within NATO, given our direct proximity to Russia and that famously exposed stretch of land known as the Suwałki Gap. Now, with Sweden and Finland on board, some of those long-standing strategic dilemmas, the ones that kept us up at night, are finally being tackled head on.
The Baltic Sea is now almost entirely a “NATO lake”. Apart from Russia's Kaliningrad Oblast and a small coastal strip around St Petersburg, virtually every inch of its shoreline belongs to the Alliance. This is not just a map change; it is a game-changer for daily life and strategic thinking. NATO's direct border with Russia in the north has effectively doubled overnight, now extending into the Arctic region with Finland's lengthy frontier. This dramatically expanded front line means vastly more opportunities for allied forces to manoeuvre, as well as far simpler defence planning. Crucially, it also provides NATO with the unprecedented opportunity to control vital maritime routes. This comprehensive control is absolutely vital, especially when considering the murky "grey zone" threats that have been on the rise.
Indeed, these are not theoretical concerns. For us, they are part of our daily reality. In the past year, we have seen worrying reports of a "shadow fleet" operating in these waters, using a variety of physical and electronic measures to mask their identity (or even try to hide from authorities entirely), alongside alarming incidents of undersea cable damage right across the Baltic. Just in late May 2025, Finland's defence minister, Antti Häkkänen, mentioned that new developments are now being seen, as Russia has started to protect its shadow fleet in the narrow passage of the Gulf of Finland with military escorts and the wider presence of armed forces. This new, aggressive posture follows recent events like suspected Russian airspace violations in Finnish territory. Estonian patrols have also been actively inspecting suspicious, uninsured vessels, leading to tense encounters, including a standoff in May where a Russian fighter aircraft reportedly entered Estonian airspace after a tanker refused inspection. These vessels, sometimes changing names multiple times in a matter of months to obscure their identities, highlight the lengths to which these operations go. A unified NATO presence across this vast new maritime front allows for a much more effective, coordinated response to these hybrid tactics, shoring up critical infrastructure from Tallinn to Vilnius and defending the fundamental right to freedom of navigation against those who would exploit it. For ordinary citizens, this means a greater sense of security in the very infrastructure that underpins our modern lives.
This is not just about static defences; it is about dynamic power projection. With Swedish positions and capabilities, particularly the strategically vital island of Gotland in the middle of the Baltic Sea, which is now a NATO asset, the Alliance gains an unprecedented ability to project air and sea power into and across the central Baltic. This fundamentally transforms the ability to receive rapid reinforcements, something that weighs heavily on the minds of those who remember a more vulnerable past. Furthermore, Finland's potent ground threat forces Russia to dilute any forces it might otherwise concentrate on the Baltic states, whose fundamental lack of strategic depth in terms of land remains a challenge. Sweden and Finland's accession offers a critical hedge strategy: the collective capabilities now available can effectively shut down the Baltic Sea if necessary. This would involve coordinated naval operations, including potential offensive mining capabilities around key areas like Kaliningrad, ensuring maritime dominance and preventing hostile access.
Sweden and Finland bring serious new muscle to NATO's Northern Flank. Finland, for instance, boasts one of Europe's largest reserve armies and unparalleled expertise in total defence, significantly bolstering NATO's ground defence. For us in the Baltics, this means any potential Russian ground aggression would now face a more expansive, integrated and incredibly resilient front. It is like having new, incredibly tough neighbours in our corner. This enhanced integration is already evident. Sweden, for example, deployed troops to the Multinational Brigade in Latvia earlier this year. This marks a historic first with Swedish land forces contributing to collective defence on another NATO member's soil. This is a powerful, tangible sign of Stockholm’s immediate commitment to Baltic security, something we deeply appreciate here.
Beyond the hardware, the courage of these nations' leaders to move away from decades of neutrality simply wipes away any lingering strategic ambiguity Russia might have tried to exploit. Their unwavering commitment to NATO's Article 5, the collective defence clause, sends a clear, undeniable message: any aggression against an allied country will be met with the full force of the entire Alliance, including the considerable military and intelligence capabilities of Sweden and Finland. This absolute clarity dramatically strengthens deterrence across the region. It is a loud and clear "don't even think about it," a message that resonates deeply with our historical experiences.
Crucially, the Baltic states themselves are leading by example, putting our money where our mouths are when it comes to defence. Lithuania, for instance, has pledged to significantly boost its defence spending to a remarkable five to six per cent of GDP from 2026, aiming to become one of NATO's highest per capita defence spenders. Estonia and Latvia are following suit, with Estonia committed to reaching at least five per cent of GDP by 2026, and Latvia targeting five per cent by 2028. This incredible commitment, coupled with consistent and vocal leadership in stressing security threats, means the Nordic and Baltic nations are increasingly stepping into a pivotal leadership role within Europe. Our first-hand understanding of geopolitical dynamics and our proactive embrace of NATO integration offer invaluable insights for the entire continent. We are at the forefront, pushing for robust deterrence, unwavering support for Ukraine, and comprehensive resilience against all types of hybrid threats. Our collective voice and shared strategic perspective are now playing a much more central role in shaping Europe's broader security agenda.
Ultimately, Sweden and Finland joining NATO is far more than just an expansion: it is a fundamental recalibration of power in the Baltic Sea region. This dramatic shift aligns with the desires of key allies, particularly the United States, who seek a concrete and swift sign of Europe's transition toward a hard defence posture. Washington will increasingly look to its Nordic, Baltic and Polish partners – nations demonstrating proactive commitment – rather than waiting for slower, more painful changes across the broader European core.
While this new reality has transformed an area once fraught with vulnerabilities into a cohesive zone of collective strength, forging a true "New Nordic Shield", the journey is far from over. For Lithuania, Estonia and Latvia, this new reality means significantly enhanced security, far less strategic uncertainty, and the tangible promise of collective defence against any future threats, allowing us to stand firmer than ever on NATO's reinforced Eastern Flank. However, the path ahead requires sustained effort. Beyond the political will and budget plans, there is still immense work to be done in developing very concrete military capabilities, ensuring interoperability, and adapting to evolving threats. This new chapter demands continuous investment, innovation, and unwavering determination to translate resolve into resilient defence.
The views and opinions in this text do not necessarily reflect those of the Heinrich-Böll-Stiftung.