How Finnish and Swedish NATO Accession Could Shape the Future Russian Threat

Introduction

Russia’s invasion of Ukraine was a major strategic blunder. Not only will Russia emerge from the war economically and militarily weakened, but its brutal invasion has undercut Moscow’s geopolitical position, including by triggering nearby countries to take new steps to provide for their security and defense. Most notably, Russia’s aggression in Ukraine compelled Finland and Sweden to apply for NATO membership— leading to an expansion of the very alliance that Russia purports to be opposing in Ukraine. While it is unclear exactly when Finland and Sweden will join NATO—this will depend on when Hungary and Turkey, the last remaining allies to ratify the accession protocols, finalize the process—it is clear that there is no going back to the status quo ante.

NATO allies should expect Russia to react to Finland and Sweden joining the organization beyond the cool response that followed their announcement. Their accession into NATO will permanently reshape the European security architecture, which Moscow is likely to see as a threat to its own security and therefore use as a basis for adjusting it calculus. Even though Moscow has not explicitly retaliated against Finland and Sweden for joining NATO beyond expressing displeasure, the Kremlin is nonetheless likely to respond, including in ways that will pose challenges to the alliance in both the near and long term. This memo discusses how Finland’s and Sweden’s entry into NATO will shape Europe’s security landscape, how Russia is likely to see these changes and respond, and how the allies can address the future challenges stemming from these changing dynamics.

Europe’s Evolving Security Architecture

Practically speaking, Finnish and Swedish NATO accession may not entail a dramatic change. Despite their previous policies of formal military non-alignment, both Finland and Sweden have long been regarded by Moscow as “virtual” NATO allies, given their close partnership with the alliance since the end of the Cold War and their interoperability with NATO standards.¹ Cooperation between NATO and Finland and Sweden further intensified following Russia’s illegal annexation of Crimea in 2014, with both countries signing host nation support agreements with the alliance and obtaining Enhanced Opportunity Partner status at the Wales Summit in September of that year.² Thus, while the formal integration of assets such as Finland’s ground and air forces (which soon will be flying the F-35) and Sweden’s naval, air, and defense industrial capabilities is significant, it will not profoundly alter the military balance between NATO and Russia.³

Nevertheless, Finnish and Swedish NATO accession is a significant step from a broader geopolitical perspective. Before Russia’s re-invasion of Ukraine in February 2022, the odds of Sweden and Finland joining NATO were small, with a majority of the citizens and political elite in both countries content with the status quo.⁴ Yet the war shattered many long-standing assumptions underpinning the previous state of affairs, prompting a rapid rise in citizens’ support for NATO membership in both countries. This dramatic change carries numerous implications for Europe’s security architecture, including the following.

Crystallization of a shift in focus for European security toward the northeast. Since Russia’s invasion of Ukraine, the Nordic and Baltic countries have emerged as key players in the collective Western response, already altering Europe’s geopolitical center of gravity.⁵ The NATO accession of Sweden and Finland— which is both a Nordic and Baltic country—could lock in this shift for the long term, especially if the conflict with Russia continues to dominate the alliance’s attention and resources.

Together, the five Nordic countries will have a major influence on alliance deliberations, adding extra weight to the Baltic states’ call for defense of the alliance’s eastern flank. The heightened focus on the Nordic-Baltic region—which, along with the High North, should increasingly be seen as one integrated strategic theater for the alliance—may also cause other allies such as Poland and Germany to more fully embrace their northern European and Baltic identities.

Increased cooperation between NATO and the European Union. With the accession of Finland and Sweden, only four EU member states—Austria, Ireland, Cyprus, and Malta—remain outside NATO. This could affect the ongoing debate within the EU about the development and direction of its defense ambitions, potentially including the development of a more robust, complementary EU pillar within NATO—a dynamic that is only furthered by Denmark’s recent decision to end its opt-out from the EU Common Security and Defense Policy.⁶ Finnish and Swedish NATO membership will also likely facilitate greater cooperation and coordination between the two institutions.

An altered map of northern Europe. The incorporation of vast new areas of land into NATO territory will end the geographical isolation of northern Norway’s strategically important Finnmark region from other allied territory, providing it with greater strategic depth. The value of this is already evident in Norway’s use of a new military transit corridor via Finnish Lapland since Finland’s Parliament voted to support NATO membership.⁷ Finnish and Swedish accession will also mean that the Baltic Sea will be almost surrounded by NATO member states, with just the exception of Kaliningrad and the small portion of its easternmost shores that lie within Russian territory. Finally, Finland brings with it an 830-mile border with Russia. While this boundary consists largely of wilderness other than at its southeastern edge near St. Petersburg, its addition will nonetheless mean that NATO’s border with Russia will extend from the Arctic Ocean to the Baltic Sea.

Russia’s Changing Threat Perceptions

The shifts to the European security architecture previously described will naturally influence Russia’s perceptions of its own security. While President Vladimir Putin has publicly claimed not to have a problem with Finnish and Swedish NATO membership, Moscow will nonetheless reassess its security interests in light of the accession to NATO of Finland and Sweden, likely perceiving the following challenges.⁸

A more vulnerable Russian northwestern flank. Russia’s border with NATO will grow considerably. Russian military planners will need to account for the alliance’s potential presence along the lengthy border with Finland, including near St. Petersburg and vital Russian supply routes to the Kola Peninsula. Meanwhile, with the Baltic Sea ringed nearly entirely by NATO allies, Russia may perceive higher risks when carrying out naval operations in the area as well as worry about threats to Kaliningrad, which stands to lose a maritime connection with mainland Russia through non-NATO waters. Finally, the northeastward shift of NATO’s center of gravity may increase Moscow’s paranoia about the alliance concentrating more military resources along Russia’s northwestern flank.

Exposed military assets. The Kola Peninsula—perhaps the most important area to Russian national security—lies just east of northern Finland. This bastion is surrounded by an anti-access/area denial (A2/AD) defensive ring and includes Severomorsk, which hosts Russia’s crucial Northern Fleet. The Northern Fleet includes ballistic missile submarines guaranteeing the country’s second-strike nuclear capability, as well as attack submarines and cruise missile–equipped surface vessels that contribute to the vital mission of interdicting U.S. reinforcement convoys bound for Europe.⁹ While the Kola Peninsula already abuts NATO territory in northern Norway, the presence of another NATO country on its borders is likely to heighten Russia’s sense of threat to its Northern Fleet assets. Moscow may assume that the alliance will eventually station troops, intelligence facilities, missiles, and even nuclear weapons in the vicinity, although there are no signs that NATO currently plans to do so. The degradation of Russia’s conventional military, given the losses it continues to incur in Ukraine, will also increase Moscow’s reliance on its nuclear forces, bolstering the importance of the Kola Peninsula in Moscow’s thinking.¹⁰

Greater geopolitical isolation. For decades, the non-aligned status of Finland and Sweden signaled a viable “third way” between the West and the Soviet Union (and later Russia). With Helsinki and Stockholm now formally joining their voices with NATO, Moscow stands to lose ground in the global propaganda war in which it has long preached the inevitable failure of the West. Indeed, Finnish and Swedish NATO membership represents a clear blow to Russia that will further erode its geopolitical position, while the greater alignment between NATO and the European Union further strengthens the collective geopolitical weight of the West vis-à-vis the Kremlin.

Russian Reactions to Finnish and Swedish NATO Accession

For many years, Russia warned Finland and Sweden that it would retaliate if they tried to join NATO.¹¹ Such an explicit response has not yet materialized, almost certainly because Russia is bogged down in Ukraine. But Russia’s current lack of attention and capacity does not mean that it will not respond in the future. The Kremlin tends to engage in worst-case-assumption thinking, and defense planners will now have to engage in worst-case-scenario planning. The United States and NATO should expect Russia to take the following near- and long-term responses.

Short-Term Responses

Hybrid warfare tactics. Preoccupied with the war in Ukraine and forced to relocate troops from northern Europe to the Ukrainian theater, Russia’s ability to pose a conventional military challenge in the Nordic-Baltic-Arctic theater is temporarily diminished.¹² To compensate, Moscow may resort to other nonconventional tools of aggression short of kinetic warfare. Recent suspected Russian sabotage to the Nordstream pipelines and undersea cables near the Faroe and Shetlands Islands illustrate this approach, while drone sightings near Norwegian oil and gas fields suggest future attacks on critical infrastructure in the region.¹³ Notably, such tactics are difficult both to attribute and defend against, providing Russia with an asymmetric advantage against the West.

Russia may also weaponize flows of migrants and asylum seekers, as it previously did on its borders with Norway and Finland during the winter of 2015–16, and as Belarus did at its border with Poland in 2021–22.¹⁴ Russia’s deepening relationships with Belarus and Syria, whose citizens continue to flee in large numbers, may facilitate such efforts. In recognition of this possibility, Finland is now considering building between 130 and 260 kilometers of fencing near crossing zones along its border with Russia.¹⁵

Other hybrid tactics beyond attacks on critical infrastructure and weaponization of migrants are also possible. These may include disinformation campaigns aimed to stir up domestic political turmoil, threats to further pollute the Baltic Sea via Kaliningrad, cyber attacks on Finland and Sweden, and GPS jamming. A particularly salient concern in the High North is that Russia could use its extensive civilian fishing fleet to execute operations below the threshold of war. This fear is heightened by events such as the observation of unusual Russian fishing boat activity near the areas where Norwegian subsea cables were damaged.¹⁶

Greater emphasis on Russia’s nuclear capabilities. Russia’s drive to double down on its non- conventional tools in the short term (given the degradation of its conventional military in Ukraine) will apply not just to its hybrid tools, but also its nuclear capabilities. Moscow’s increasing reliance on nuclear weapons following conventional military losses in Ukraine—demonstrated by Putin’s stepped up nuclear threats—is likely to result in increased posturing in the Nordic-Baltic-Arctic theater.¹⁷ Ahead of its Grom strategic nuclear exercises in October 2022, for instance, Russia moved several long-range nuclear-capable Tu-95 and Tu-160 strategic bombers north to the Kola Peninsula.¹⁸ The exercise itself, meanwhile, included testing of all three legs of Russia’s nuclear triad over the Arctic.¹⁹ It is reasonable to expect that Russia will resort to additional nuclear intimidation and signaling going forward to deal with its heightened regional threat perception following Finnish and Swedish NATO membership.

Long-Term Responses

Increased focus on conventional deterrence along Russia’s northwestern flank. Because changes to the European security architecture resulting from Finnish and Swedish NATO accession will endure, Russia will eventually adapt once it recovers from its military losses in Ukraine. One such adaptive effort may be a heightened focus on bolstering its conventional deterrence posture along its northwestern flank. Believing that it must now pay greater attention to that area given the new threat axes from northern Sweden and Finland, Russia could permanently reinforce its bastion on the Kola Peninsula, strengthening the A2/AD ring around Severomorsk with additional air and missile defense systems. It could also deploy additional forces along the border with Finland near St. Petersburg.

More provocative military activity in the Nordic-Baltic-Arctic region. Once Russia reconstitutes its forces, Moscow is likely to grow more assertive in addressing a perceived threat from an expanded NATO. Particularly if Moscow is looking for opportunities to demonstrate its great-power status, it may more frequently carry out provocative air and maritime exercises in the Nordic-Baltic-Arctic theater. During the past decade, Russia has periodically harassed Western naval assets in the Norwegian and Baltic seas.²⁰ It has also used its aircraft based at Kola to fly close along the border of Norway and into the Greenland-Iceland-UK gap to probe air defense networks.²¹

While such activities may temporarily decrease in the short run as Russia focuses its attention on Ukraine, in the long run they may be expected to increase, with Russia attempting to intimidate Finland and Sweden to regain an edge in northern Europe. The Svalbard archipelago and the area around Thule Air Base in Greenland may be targets of provocative Russian military activity going forward, given their strategic significance to the West.

Heightened reactivity to NATO’s actions in northern Europe. Moscow has made it clear that it will closely follow what role Sweden and Finland will play in NATO, and it will undoubtedly be on the lookout for any airfield upgrades, new intelligence facilities, or changes to tactics in NATO exercises in the region. While Russia may assume that allied infrastructure will eventually be present on Finnish and Swedish territory, concrete evidence of this will certainly generate a response.

As the years go by, it is likely that there will be more military exercises in the northern parts of Norway, Finland, and Sweden. Moreover, with the stationing in 2026 of the first batch of Finnish F-35s in Lapland, the area will become host to the second-largest concentration of F-35s in the world after Alaska.²² Russia is likely to greet additional NATO troops, equipment, and facilities in the region with a more aggressive posture.

Recommendations

Russia’s perceptions of the shifting geopolitical environment in the wake of Finnish and Swedish NATO accession will influence its behavior and the nature of the challenge that it poses to the alliance going forward. To manage both the short-term and long-term evolution of the Russian threat resulting from the alliance’s new round of enlargement, the United States and NATO should:

Increase defenses against hybrid threats. As Russia seeks to compensate for temporary conventional military weakness with alternative forms of exerting pressure, the West will need to defend against hybrid threats including attacks on critical infrastructure, cyberattacks, weaponization of migrants, disinformation campaigns, and other forms of sabotage. The United States and NATO have been increasingly attuned to hybrid threats since 2014, yet the allies remain vulnerable to such Russian actions. The first step the allies should take is to reevaluate their ability to deter hybrid threats, including through a reexamination of actions to which Russia is most likely to respond. In instances where attribution is difficult, the allies must work together to verify the perpetrator quickly, and then—critically—to demonstrate to Moscow the West’s willingness to respond proportionally.

Effectively countering these threats will require contributions from all stakeholders in the European security order—NATO, the European Union, national governments, the private sector, and individual citizens. Because military means alone cannot manage the threat of gray zone aggression, NATO must work closely with the European Union, whose competencies in the economic and political domains make it the more suitable actor for addressing many types of subversive activities. Moreover, a key aspect of defense against hybrid threats is resilience. National governments must continue their work to foster resilience in and among their societies, promoting a comprehensive approach to security that recognizes the roles of citizens and the private sector in addition to the military. Finland has successfully done this already, having introduced during the Cold War education programs such as henkinen maanpuolustus (“mental national defense”) to increase societal awareness of national security issues.²³ Other governments should seek to learn from Helsinki and implement similar programs. Finally, it will be critical to counter Russian psychological warfare through the coordinated development of better tools to preemptively set the narrative around key events. The immense strategic value of such information dominance has been demonstrated by the successful Western efforts to combat Russian disinformation throughout the Ukraine war.

Effectively manage the heightened Russian nuclear threat. Given that Russia is likely to increase its reliance on nuclear weapons, the NATO alliance should review its nuclear posture. While the publication of its “Chemical, Biological, Radiological, and Nuclear (CBRN) Defence Policy” in June 2022 represents a relatively recent attempt to articulate the alliance’s positions, updates may be required in light of the rapidly evolving Russian nuclear threat.²⁴ A new review should include the role of nuclear weapons in extended deterrence and escalation management, as well as preparations for fighting in nuclear environments and steps to manage the information domain in the case of Russian nuclear use.²⁵ Particular attention should also be given to how Russia’s increased nuclear posturing in northeastern Europe affects NATO’s own strategy for defense of this vulnerable region.

As emphasized in the 2022 National Defense Strategy, the United States should also increase efforts to consult with allies to ensure coherence of views among all NATO countries, especially as Russia’s nuclear threat and threats to strategic stability more broadly evolve resulting from the war in Ukraine. Ensuring cohesion of the three allies that have nuclear weapons—the United States, the United Kingdom, and France—is especially critical. France’s absence from the Nuclear Planning Group (NPG) complicates the formulation of such a common approach, given that its nuclear weapons policy nonetheless contributes to the posture of the alliance as a whole. Allies should therefore encourage Paris to join the NPG, or at the very least pursue consultations outside formal NATO structures.

Plan for a militarily resurgent Russia. Russia’s conventional military forces may be weakened, but they will not be weak forever. After the war ends, Russia will rebuild—in fact, lessons learned from Ukraine could even prompt the country to embark on a major reorganization of its armed forces, similarly to how the United States military adapted following its failures in Vietnam. In the long term, therefore, NATO must ensure that its conventional deterrence posture remains strong and resilient—in particular in the Nordic-Baltic-Arctic region, given Russia’s probable plans to refocus its attention on its northwestern flank.

The integration of the very capable Swedish and Finnish militaries with NATO’s already strong regional deterrence posture will go a long way, enabling NATO to better fulfill its updated forward defense plans for its northeastern flank.²⁶ Nonetheless, the alliance should take additional steps to improve deterrence in the region. Initiatives could include the following:

• Make command structure changes in the Nordic-Baltic-Arctic region to accommodate potential NATO military operations. Changes could include the creation of a High North Strategic Command Head- quarters in Norway and a subordinate component command that specializes in land/naval/air Arctic warfare, as well as the establishment of a combined air operations center in the region.
• Review and upgrade reinforcement infrastructure in Sweden and Finland, including a common logistics and transportation network. If necessary, NATO could pre-position equipment in both countries.
• Sweden and Finland could host NATO exercises, especially air and missile defense operations. It will be important to continue large-scale exercises in northern Europe such as Trident Juncture and Cold Response, and Swedish and Finnish participation will test how NATO adapts its planning with these two new members. Encouragingly, planning is already underway for the Nordic Response drill in 2024, which will be the first exercise in the High North involving Finland and Sweden as NATO members.²⁷ New exercises such as Nordic Response could also focus on practicing large-scale reinforcement of the region. Crisis management exercises and discussions will be increasingly crucial as well. Finally, continued engagement with the UK-led Joint Expeditionary Force (JEF) is important, as is continued participation in the Nordic defense cooperation (NORDEFCO) arrangement.
• Improve key NATO capabilities in the High North, including air and missile defense; early warning; information-sharing; intelligence, surveillance, and reconnaissance (especially space-based and drone surveillance capability); and secure and resilient strategic communications that can overcome the difficulties of communicating in the Arctic.
• Revise the alliance’s contingency planning in the Nordic-Baltic-Arctic region, paying particular attention to strategic chokepoints in the Baltic Sea such as the Danish Straits as well as to the “chain of defense” consisting of Gotland, Bornholm, and the Åland Islands.²⁸
• Institute a NATO Air Defense mission for the Baltic Sea region, building on the existing Baltic Air Policing operation.

Avoid provoking Russian aggression in the Nordic-Baltic-Arctic theater. NATO’s challenge in the Nordic-Baltic-Arctic region is to bolster deterrence while taking care not to provoke a Russian overreaction. To a certain degree, an increase in tensions with Russia following Swedish and Finnish NATO accession is unavoidable and may be chalked up as the cost of ensuring strong deterrence based on a credible military capability. Nonetheless, it is important to minimize these tensions in order to avoid causing an arms race that makes the region less secure.

The best way to accomplish this is to ensure that incorporating Sweden and Finland into NATO evolves slowly, predictably, and without surprises. Sweden and Finland have a long history of relations—both good and bad—with Russia and are best suited to dealing with Moscow in the context of the new security environment in northern Europe. Their guidance to the rest of NATO on this effort will therefore be crucial. More broadly, working toward regional forms of engagement after a cease-fire in Ukraine will be important to rebuild normative structures of European security.

Create a comprehensive NATO strategy for regional security in northern Europe. In recent years, outside analysts and experts have increasingly called on NATO to develop an Arctic strategy in light of the more difficult security situation in the High North.²⁹ The accession of Finland and Sweden to the alliance, however, highlights the need for such a strategy to take a comprehensive view of northern Europe as a single theater that also encompasses the Baltic Sea and North Atlantic. The alliance should therefore set out to create a northern European security strategy to account for the evolving Russian threat to the region in years to come.

Such a strategy could build on the ongoing efforts by Nordic countries to draft plans for divisions of labor across the region ahead of the Nordic Response drills planned for 2024.³⁰ As these discussions progress, NATO will need to navigate differing priorities for countries in the region. Recent pledges by the Nordic governments to deepen defense cooperation are a positive signal in this respect, and further steps should be taken to coordinate a common strategic understanding.³¹ These steps could include joint determination of Nordic capability targets within NATO’s defense planning process, as well as the pooling of aerial and maritime surveillance capabilities.³² Crucially, there should be an effort to continue to encourage states such as Poland and Germany to embrace their identity as Baltic Sea states and take a greater stake in northern European security.

Foster a sense of broader allied solidarity in Finland and Sweden. As new NATO members, it will be important for Sweden and Finland to adjust their perspectives and adopt responsibility for the defense of a broader area beyond their own territories. Neutrality has been an ingrained part of national self- understanding in both Sweden and Finland for a long time. Joining NATO, therefore, entails a significant shift in identity and will require both countries to reprofile their security policies by contributing to overall regional defense in addition to home defense.

Current NATO allies should encourage Finland and Sweden to hit the ground running by taking on active roles from day one, especially given that both countries possess the capabilities and resources to do so. In particular, Finland and Sweden should make significant contributions to security on both the alliance’s eastern and southern flanks, including implementation of plans for NATO’s enhanced forward presence in its new brigade-level formation. Moreover, they should take care to fulfill all NATO goals with respect to defense investment and capability development, while credibly committing to doing so in the future.

In the long term, if Russia comes back with a vengeance, NATO membership with its collective security guarantees really matters for Finland and Sweden. But in return for this guarantee, they must be willing to play their own parts in the alliance’s collective defense. Entering the door as model allies will send a strong political signal that Finland and Sweden are committed to doing so.

Conclusion

For Putin, “losing” Finland and Sweden to NATO was collateral damage in the battle to subjugate Ukraine. But while membership in the alliance undoubtedly acts as a shield for Finland and Sweden against Moscow’s malign intentions, it also creates new dynamics in European security that will reshape Russia’s own threat perception and the nature of the challenge it poses to the West. Failure to address this evolving threat could result in a paradoxical situation in which Europe—particularly along its northeastern edges—becomes even more insecure despite NATO’s expanded role in the region. Managing both the short- and long-term consequences of this evolution are therefore critical tasks for NATO, Sweden, and Finland going forward.

About the Authors

Nicholas Lokker is a Research Assistant for the Transatlantic Security Program at CNAS. His work focuses on European political and security affairs, with a particular emphasis on the European Union and the transatlantic approach toward Russia.

Jim Townsend is an Adjunct Senior Fellow for the Transatlantic Security Program at CNAS. He served for eight years as Deputy Assistant Secretary of Defense for European and NATO policy, and he worked for more than two decades on European and NATO policy in the Pentagon.

Heli Hautala is a Finnish career diplomat and a former Visiting Fellow for the Transatlantic Security Program at CNAS. She specializes in Northern European security and Russia.

Dr. Andrea Kendall-Taylor is a Senior Fellow and Director of the Transatlantic Security Program at CNAS. She previously served as Deputy National Intelligence Officer for Russia and Eurasia at the National Intelligence Council and as a senior intelligence officer at the CIA.

Acknowledgments

This report was made possible with the generous support of the Bertelsmann Foundation, BP America, Canadian Department of National Defense, Dutch Ministry of Foreign Affairs, Embassy of the Federal Republic of Germany, Embassy of the Republic of Finland, Estonian Ministry of Foreign Affairs, Estonian Ministry of Defence, Finnish Ministry of Foreign Affairs, Latvian Ministry of Defense, Ministry of National Defence of the Republic of Lithuania, Swedish Ministry of Foreign Affairs, and Royal Norwegian Ministry of Defence.

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