Cooperation Can Make the NATO Lake a Reality


In May, Finland’s former intelligence chief declared that when his country and Sweden join the alliance, “The Baltic Sea Will Become a NATO Lake.” Nordic defense professionals have since highlighted how the two countries will provide the alliance sophisticated weapons and well-trained forces, as well as shorter routes to potential flashpoints and a significantly reinforced northern flank. 

But to appreciate how effective they will be in closing the Baltic to Russian activity, it is important to understand their long history of cooperation as well as the regional military geography. This legacy of cooperation, with each other as well as existing NATO members, will facilitate their quick integration into the alliance. However, there is still work to be done to enable NATO to take full advantage of its new members and larger countries such as the United States and United Kingdom have a particularly crucial role to play. Specifically, it is deepened regional military cooperation coupled with a clearly defined division of labor that will turn “the NATO Lake” from a moniker into a military reality. 


Military cooperation between Sweden and Finland has a long history — Sweden provided Finland weapons when it fought an attempted Soviet invasion to a standstill in 1939. In its current guise, cooperation began modestly in the late 1990s, mainly in the naval arena. Initially begun as a cost-cutting measure, the cooperation has expanded and deepened since 2014, driven by growing concerns over an openly revanchist Russia. While cooperation is still most far-reaching between the two countries’ navies and air forces, their armies too have trained more closely over time, including in large-scale exercises. 



These exercises give an idea of how cooperation could develop under the NATO umbrella. In Aurora 17 — a Swedish exercise involving over 19,000 troops from Sweden, Finland, the United States, and several other countries — Finnish soldiers trained to defend the strategically important Gotland island. In the army-centric Northern Winds 19, a Swedish brigade reinforced with a Finnish battalion defended northern Sweden, with the red side played by a Norwegian brigade reinforced by U.S. and British troops. Several Swedish and Finnish units have effectively been “twinned,” working regularly with a partner unit in the other country with which they share a common specialty or geographical areas of responsibility. Close bonds have been established between personnel at all levels in these units, greatly facilitating collaboration.

Perhaps most telling, the Swedish, Finnish, and Norwegian air forces have been training jointly for over a decade, routinely participating in each other’s main national air force exercises, as well as hosting high-end, large-scale biannual multinational exercises. Absent formal alliance membership, cooperation remains at a level of interoperability but without any joint command structures. With U.S. and British support, NATO can deepen this cooperation and expand it to other countries in the region.


The benefits of Swedish-Finnish cooperation can be most easily seen in the potential for better defending the Baltic States. Several studies have highlighted the challenge of defending this region in the event of Russian aggression, specifically when it comes to providing air support and reinforcements before Russian long-range air defenses and anti-ship missiles can be suppressed. But using Swedish bases, NATO air forces could increase their operational tempo and reinforcements could better circumvent the most acute threats emanating from the Kaliningrad exclave. Close coordination between Denmark, Norway, and Sweden can also secure the approaches to the Baltic Sea from the North Sea, and keep open sea lines of communication to the Swedish West Coast, particularly the harbor of Gothenburg. Both of these tasks will be critical to ensuring the flow of reinforcements and supplies. 

Cooperation would provide further benefits in the maritime realm as well. Today, the Baltic Sea is generally thought of as a contested body of water, with Russia having a moderately sized fleet operating out of its bases in Kaliningrad and the Gulf of Finland. Of the three regional NATO navies capable of surface warfare, only Poland is fully dedicated to the Baltic Sea, with Germany and Denmark having their priorities split between the Baltic and the North Atlantic. However, with Finland and Sweden joining NATO, there will be a drastic shift with a significant number of modern vessels designed for littoral conditions being added to the roster, including Sweden’s fleet of modern submarines. Following their investments in modern coastal anti-ship missile batteries, Finland and Estonia would be able to close the Gulf of Finland to hostile shipping. This would in effect split the Russian Baltic Fleet in two, and stop any movement by water between the Kaliningrad exclave and the Russian mainland. Any major Russian surface operations would be high-risk and in the case of a Russian amphibious landing — perhaps against Gotland, Åland, or the Bornholm islands — sustaining any temporary bridgehead would be a high-cost and decidedly lethal endeavor.

Finally, Sweden and Finland will also be able to work together to defend the European part of the High North, the vast and sparsely populated area largely above the 65th parallel covering parts of Norway, Sweden, Finland, and Russia. While it might be perceived as something of a secondary issue for NATO, the High North is of crucial importance to Russia, as it houses the Russian Northern Fleet based around Murmansk. This is home to a large part of the submarines that make up Russia’s second-strike capability. The area is also crucial for monitoring the Arctic routes of U.S. long-range air and missile strikes, and would be the starting point for any Russian attempt to intercept U.S. reinforcements to Europe. As a result, the question of how to defend northern Norway in case Russia tries to push further west has been a long-standing issue for NATO planners. The shortest and most easily traversed route to northern Norway passes through Finland and Sweden. This has created an untenable situation, where all three countries have conducted their own independent planning for what in practice would be a single theatre of operations. Integrating both Swedish and Finnish forces into NATO plans — focusing on geography and terrain rather than national borders — will greatly facilitate defending the northernmost flank of the alliance.

Next Steps

In addition to the steps discussed above, there will be other long-term benefits to consolidating NATO defense planning. One crucial step is fusing sensors and systems across national boundaries. For example, Finnish and Norwegian ground-based radar systems are based further east than their Swedish counterparts, while Sweden in turn has a significantly better picture of the situation on and above the Baltic Sea thanks to its location and airborne sensors. Thus integration will give all countries in the region a more holistic situational picture both in the air and at sea. This fusion has already begun with the recently announced Finnish-Estonian agreement to integrate their coastal defenses, including both sensors and land-based anti-ship missiles. The Swedish, Finnish and Norwegian air forces would also benefit from bringing together Finnish sensor data and Norwegian F-35s with Swedish air-force bases and intelligence, reconnaissance and surveillance capabilities, as well as combining the complementary sets of qualified munitions the three countries currently use. Last but not least, reinforcing the Baltic States — presumably through Swedish territory — would be greatly facilitated by fusing sensor data and coordinating assets in the maritime and aerial domains. 

Challenges, however, remain. The Nordic and Baltic states have different strategic cultures and are currently focused on different operational directions. Whereas Finland and the Baltic countries have focused primarily on their eastern land borders, Sweden has prioritized air-power and interdicting an amphibious assault. Denmark, in turn, is focused on the maritime domain, particularly the entrance to the Baltic Sea, and Norway on defending its coast-line and northern-most regions. In terms of strategic culture, the countries on Russia’s border reacted strongly to Russia´s annexation of Crimea, whereas their neighbors, despite increasing defense budgets, have been slower to act. Finally, all the Nordic-Baltic countries have put a premium on their bilateral relationship with the United States, meaning that refocusing their defense efforts toward NATO may take some diplomatic finessing.  

To smooth over these potential challenges, both U.S. and U.K. leadership will be important. Simply put, these countries have key capabilities in several domains — such as advanced intelligence reconnaissance and surveillance, aerial force multipliers, and large expeditionary units — that are lacking in the arsenals of Finland and Sweden as well as other smaller European allies. In the maritime domain, Germany is also becoming a major player in the region. Having NATO’s larger powers act as honest brokers and back-stop crucial capabilities is vital. As NATO’s new members adjust their current defense plans, U.S. leadership can also help craft a regional strategy that allows partners to handle specific operational goals and reassign scarce assets to missions that may not be their top priority, but will be necessary for the alliance as a whole. Sweden in particular might be required to adapt its force structure as a NATO member. Sweden has spent the last half-century looking out over the Baltic Sea in anticipation of a possible amphibious and airborne assault on its eastern shores. While there is still an important role for the units and systems dedicated to this threat, NATO membership will change the geostrategic landscape. 

With even greater cooperation and coordination, Sweden and Finland will be able to not only strengthen their own defense but also better protect an area stretching from the Arctic tip of Norway to the Baltics’ border with Russia. Russian fleets in Murmansk, St. Petersburg and Kaliningrad will be better contained, and Moscow’s ability to threaten NATO’s northern flank will be gradually weakened.



Michael Jonsson is a deputy research director at the Swedish Defence Research Agency. He holds a Ph.D. from Uppsala University and his latest publication (with Robert Dalsjö and Johan Norberg) is “A Brutal Examination: Russian Military Capability in Light of the Ukraine War,” Survival, 64:3, 7–28 (May 2022). Robin Häggblom did his conscript service as a landing craft skipper in the Nyland Brigade of the Finnish Navy, before graduating with a M.Sc. (Tech.) from the University of Oulu. He has since been working in the Finnish maritime and defense industry, and is an independent defense analyst (

Image: Swedish Armed Forces/Helikopter wing