This article is part of the Baltic Sea Region Security Initiative developed by the Carnegie Endowment’s Europe Program.
NATO’s Nordic enlargement marks the first time in modern history when all Northern European states will be members of the same alliance with mutually binding security obligations—and it is taking place at an opportune moment, given that Russian revanchism is now manifesting along multiple fronts. Russia’s maneuvers—its war against Ukraine, its attempts to increase pressure on the Baltic states and Poland, the de facto absorption of Belarus into its orbit, and its increasing militarization of the Arctic—are effectively reshaping the foundations of European security and will demand changes to NATO’s deterrence and collective security approach for years to come.
For NATO, the added value of the recent enlargement is undisputable. Finland, as a frontline member with significant military capabilities, especially in the land and air domains, will carry a tremendous responsibility in deterring Russia in Northern Europe. Finland’s key contributions to NATO will be defending its territories and supporting allied operations in the region. Sweden’s contributions, with its armed forces and geostrategic location, will likely be acting as a staging ground and reinforcing member states for NATO operations once it formally joins the alliance. Swedish support may be deployed in different directions to bolster neighboring states like Finland, Norway, and the Baltics.
Unlike most European countries at the end of the Cold War, Finland maintained a rather sizeable military. The wartime strength of the Finnish Defense Forces is currently 280,000 personnel, and it has a reserve of up to 900,000 conscripts. In addition, Finland has one of the largest artillery forces in Europe, including precision-strike capabilities. The country has also just reformed its procurement process for its navy and air force: For example, in 2021, Finland replaced its F/A-18 aircraft with 64 F-35s. In joining the F-35’s industrial network, Finland can further integrate its security structure with that of Denmark’s and Norway’s as well as other NATO states using the aircraft.
Although Sweden downsized its military after the Cold War and transformed it to better suit overseas special operations, its armed forces are both modern and interoperable with those of other NATO members. Sweden also has an advanced defense industry, a capable air force, and a maritime force in possession of submarines. Moreover, the addition of Swedish territories and islands would make the entire Baltic Sea coastline NATO territory, except for the Russian coastline and its exclave of Kaliningrad. Troops and equipment could therefore be transported more easily by sea to Estonia, Latvia, and Lithuania as well as to the European Arctic. Thus, Swedish accession to NATO would make the Baltic states easier to defend in the event of a Russian attack.
Northern Europe as Part of Broader Euro-Atlantic Security
It is safe to say that NATO’s Nordic enlargement will have revolutionary impacts for regional security, as it will bridge the gap in the alliance between Norway in the Arctic and Estonia, Latvia, and Lithuania in the Baltic Sea. Hence, it is essential that policymakers in and outside Northern Europe grasp the basic fundamentals of the regional security environment. While Russia remains a military threat, the broader paradigm shift in European security will remain significant: Northern Europe is now NATO’s main stage in a military conflict with Russia and the alliance’s new center of gravity.
Therefore, there is a growing need to pursue innovative ways to enhance collective defense. In practice, this means new approaches to joint operational planning, command structures, and force structures. More importantly, NATO must start thinking about how Russia will react to the Nordic enlargement in the long term, including NATO’s changes to its positioning of military assets, as this will have consequences for defense planning both within the organization and in its member states.
To understand the emerging defensive potential of Northern Europe and its strategic importance for broader Euro-Atlantic security, the region must be put into historical context. For both eastern and western European great powers, Northern Europe has functioned as a peripheral area, through which it has been possible to carry out military operations against adversaries in Central Europe. Because of this dynamic, the control of Northern Europe has remained important to great powers, and as such, the region has repeatedly played a significant role in European wars.
During the Cold War, NATO’s collective defense focus was mainly on Central Europe. Northern Europe was considered a flank area. Additionally, the constant debate within NATO over whether Northern European territories were defendable or expendable led to the characterization of Northern Europe as the “forgotten flank.”
In the future, however, with Norway, Denmark, Iceland, Finland, Sweden, Latvia, Lithuania, Estonia, Poland, and Germany in NATO, this European region will likely be at the frontline of any conflict between NATO and Russia. Considering the vast NATO territory in Northern Europe and the capabilities of the region’s countries, the debate should no longer be about whether Northern Europe can be defended. Instead, it should focus on how to ensure broader Euro-Atlantic stability, which may increasingly depend on the alliance’s ability to secure and stabilize Northern Europe through employing credible defense plans and deterrence.
The need to step up and balance Russia in Northern Europe is not a new realization. When Russia invaded Crimea in 2014, it quickly became evident that NATO’s collective defense in the region was not prepared for a potential Russian attack. This realization prompted NATO to focus on reinforcing Baltic Sea security. In 2017, the alliance deployed a “tripwire” enhanced forward presence (eFP) in the area, consisting of four multinational battalion-size battlegroups in the Baltic states and Poland—a NATO strategy defined as “deterrence by reinforcement.” After Russia’s full-scale invasion of Ukraine in 2022, it became evident that a strategy of taking back lost allied territories would incur heavy costs for occupied territories. The strategic calculus toward Northern Europe has therefore changed and after its Madrid summit in 2022, NATO signaled that the alliance would move toward a strategy of deterrence by denial.
Securing Northern Europe Through Ambitious Burden-Sharing
The process of building a safer Northern Europe will not require starting from scratch. The opportunity to step up efforts is politically backed by NATO’s new strategic concept, which describes a deterrence-by-denial posture aimed at preventing future aggression by potential adversaries. For NATO in Northern Europe, with Finland—and sooner than later Sweden—as allies, the strategic concept provides historic possibilities for defense and operational planning.
NATO’s Northern European members should take the initiative by demanding and presenting ambitious contingency plans, capability investments, and updated command structures. When looking at the possibilities and requirements for defense planning in Northern Europe, NATO should follow a logical guideline based on threat perceptions, geography, and capabilities.
For Northern Europe, Russian revanchism is both a short- and long-term challenge. Moscow will likely see the latest enlargement of NATO and the alliance’s enduring strategic changes as limiting its scope of maneuver, and it will thus respond in turn. Allies need to be prepared to counter Russia’s attempts to undermine NATO’s position and presence via gray-zone activities and nuclear saber-rattling in Northern Europe. NATO should expect Russia to pursue a rebuilding of its conventional forces in the north and to adapt its force posture in response to the alliance’s presence in Finland and Sweden. NATO’s enlargement near Russia’s Kola Peninsula and St. Petersburg, as well as Kaliningrad now being surrounded, may lead Moscow to perceive itself as strategically weakened in important areas.
In the Baltic Sea, NATO needs to enhance the protection of the Baltic states and maintain control of the Suwalki Gap between Poland and Lithuania. From an operational standpoint, and in reflection of the concept of “forward defense,” a challenge for NATO in the frontline states will be to stop a Russian attack early enough to gain time for reinforcements to arrive. But, with hundreds of miles of new coastline along the Baltic Sea, NATO will possess a variety of options to support its easternmost members.
In the Arctic, NATO has lacked a clear strategy, but this might be changing. The logic of hard security in the Arctic is currently defined by two key elements: the importance of conventional long-range missiles and nuclear weapons for Russia and the importance of the North Atlantic sea lines of communication for European defense. During the past decade, Russia has shifted back to its Cold War–based “Arctic bastion strategy,” which seeks to ensure the survival of its strategic ballistic missile submarines. As argued by experts in the past, in a conflict scenario, this strategy could pose serious challenges to the Nordic countries. Russia could, for example, hinder NATO’s military operations by enabling escalation-control with conventional long-range strategic weapons such as Iskander-M and Kalibr missiles—posing problems for the territorial integrity of Norway, Finland, and Sweden as well as limiting NATO’s access to the GIUK Gap in wartime.
Despite not having a forward presence in the Arctic, NATO has been stepping up its activities in the region through, for instance, military exercises such as Trident Juncture and Cold Response held in Norway and the Joint Forces Command Norfolk based in the United States. Thus, given the prevailing dynamics in the Arctic, Russia desires to maintain a rather dominant military role there to preserve the current status quo.
Alongside conventional military threats, there is an emerging need for improved protection of maritime critical infrastructure in Northern Europe. In particular, ensuring the security and protection of gas pipelines, data cable networks, and offshore wind farms has become increasingly important in the region. For example, Norway is the largest gas supplier to Europe, and its gas pipeline networks run through the North Sea. As seen recently with the Nord Stream 2 and the Balticconnector gas pipelines and data cables in the Baltic Sea, the potential for subsea infrastructure sabotage by foreign actors is an acute problem. NATO recognizes the threat but lacks a defined strategy for deterrence and countermeasures to protect critical national infrastructure from hostile intentions.
Based on the perceived threat posed by Russia, NATO’s defense planning should emphasize the geography and military capabilities of each ally and assign them responsibilities for which they are best suited. The different parts of Northern Europe naturally have distinctive features and security dynamics, allowing room for tailored defense approaches. Yet, the Baltic Sea region, the European Arctic, and the North Sea are interconnected in a way that demands taking a broader view. In a conflict scenario in the region, tensions in the Baltic Sea could escalate to the High North, creating the need to secure Arctic waters and the North Sea to help reinforce the Baltic Sea region.
Following this logic and to address regional burden-sharing, NATO members could be placed into four categories: frontline nations, hubs, security providers, and security guarantors. Frontline nations share a border with Russia or Belarus and are thus the most exposed to a potential military aggression; they would commit the most resources and efforts to defend the frontline of NATO. Hubs are geographically more secure countries that can act as reception or staging areas for military operations in the frontier and can offer military support for NATO’s more vulnerable allies. Security providers are the more powerful nations that, in addition to acting as vital hubs, can offer full-spectrum military support for their allies. The security guarantor is the country that can provide strategic insurance—extended deterrence—for all regional allies.
All these types of members have a certain acknowledged role in deterring and defending against Russian military aggression based on their geographical location and military capabilities. Following the typology above, frontline nations would be the Baltic states, Finland, and Poland; hubs would be Denmark, Norway, and Sweden; security providers would be Germany and the United Kingdom; and the ultimate security guarantor would be the United States. Frontline states would form the first line of defense in the event of a conflict, with hubs, the security providers, and the guarantor supplying material and personnel replenishment in the initial and subsequent phases of the conflict.
Following NATO’s new logic of deterrence-by-denial, and through pursuing the division of labor described above, it is possible to create a “deterrence-by-denial bubble,” which would significantly reduce Russia’s willingness to escalate militarily in Northern Europe. Generating this bubble would include further developing air and missile defense, airspace and subsea dominance, and intelligence, surveillance, and reconnaissance capabilities; and intensifying readiness through operations and exercises. It would also include identifying joint regional capability targets as part of NATO’s defense planning process, as well as pooling Northern European allies’ capabilities and procurements.
To make this security entity function, Northern Europe and the Baltic Sea, Arctic, and North Sea should be perceived as interconnected. To do so, NATO’s contingency planning and command structures need to be revisited. During NATO’s Vilnius summit in 2023, decisions were taken to update the alliance’s regional defense plans. Right now, it seems that Northern Europe would be divided between the European Arctic and the Atlantic on the one hand and the Baltic and Central Europe on the other.
Separating the region and its member states artificially by unfit command structures and not following military planning logic would be damaging for Northern European potential and, as such, for NATO’s collective security. It would be a disruptive reversal of the good work already underway: for example, the bilateral and trilateral defense cooperation between Finland, Sweden, and Norway. Instead of throwing away years of good work and ignoring the interconnected defense of Finland, Sweden, and Norway—who have responsibilities in both the Arctic and Baltic Sea—NATO should pursue pragmatic structures that fit their geostrategic location and existing Nordic regional defense arrangements.
In order to form functioning command structures for Northern Europe, reestablishing the Headquarters Allied Forces Northern Europe (AFNORTH)—which was active from 1952 to 1994 and served as common air and naval commands for the entire Nordic area as its subordinates—could be considered. AFNORTH, situated outside Oslo at Kolsås, was tasked to defend the vast and sparsely populated Northern Flank. Overall, it was responsible for the defense of Denmark, Norway, northern Germany (the Schleswig-Holstein area), and the strategically crucial North Sea and Baltic Sea approaches. Whether AFNORTH returns or not, NATO planners must comprehend that the new geographic and military realities in Northern Europe will nevertheless require ambitious burden-sharing and the operational integration of national fleets, navies, and armies under regional structures.
Conclusion
To capitalize on the opportunity presented by NATO’s Nordic enlargement, it is crucial for Northern European allies to embrace the development and prioritize the coordination of robust defensive responsibilities and capabilities. This effort should include enhancing interoperability and conducting joint exercises and training, as well as developing integrated defense planning. NATO’s Northern European members should conduct close political-military consultations and work to make sure that the alliance clearly follows military logic in its planning process. More importantly, NATO should emphasize the strategically vital role of Northern Europe for overall Euro-Atlantic stability; making a solid case will be crucial for maintaining unity within NATO as its force structures, defense plans, and core tasks undergo major change.