This article is part of the Baltic Sea Region Security Initiative developed by the Carnegie Endowment’s Europe Program.
With the addition of Finland and soon Sweden into the NATO fold, nearly all of the Baltic Sea littoral states will be alliance members. This has prompted some observers to label the Baltic Sea a kind of “NATO lake.” This is unfortunate framing that implies the Baltic is NATO’s alone, that the Western alliance has little to worry about from a security perspective, or that the littoral states can lean back and rest in the warm embrace of Article 5 and the United States’ commitment to their security.
This, of course, does not reflect reality, underlined recently by suspicious damage to the Baltic Connector gas pipeline and telecom links. The fact remains that, today, the Baltic littoral states face a number of significant threats that membership in NATO alone will not ameliorate. Instead, the members of the alliance on the Baltic Sea—Finland, Estonia, Latvia, Lithuania, Poland, Germany, and Denmark, as well as aspirant Sweden—and the United States confront a dynamic regional security picture that will require further refinement of capabilities and increased capacity as well as more considered efforts in collective cooperation through both NATO and the European Union.
Russia’s Posture in the Baltic Sea
The nature of the regional threat confronting NATO’s Baltic Sea littoral states is dramatically different than it was at the height of the Cold War. At that time, the Soviet Baltic Fleet was estimated to have between ninety and 130 submarines. Today, the Russian Baltic Fleet has just one. Beyond that single diesel-electric attack submarine, what one might consider classical offensive Russian naval power in the Baltic is somewhat limited. It includes just six principal surface combatants—specifically, five guided missile destroyers and one guided missile frigate—thirty-five smaller patrol and littoral combat ships, and thirteen amphibious landing craft.
Russia’s naval forces have been chronically underfunded since the end of the Cold War. The current Russian assets add up to something less than a dominant naval force in the Baltic or one capable of breaking out through the Danish strait to engage and dismantle allied supply routes across the North Atlantic. Instead, a variety of other potential threat scenarios seem more likely given Russia’s posture in the region. These might include a small-scale amphibious assault to seize strategic islands rather than cities or vast stretches of coastline; threatening allied efforts to resupply and reinforce the Baltic States and Finland by sea with sea-, air-, or land-based anti-ship missiles; threatening military and civilian targets along or near the Baltic littoral, including all manner of infrastructure facilities; and both covert and overt hybrid attacks and special operations from or in the sea.
The one exception to Russia’s largely underfunded navy in the region is its preservation of the capacity to engage in undersea activity—such as cutting lines of communication or undersea energy linkages between Baltic states and the rest of the region. The Russian submarine fleet, especially its sea-based nuclear deterrent, remains a high priority for Moscow, if only because it is tied to Russia’s one remaining claim to great power status.
Given that Russia’s most specialized naval assets for undersea operations reside within the Murmansk-based Northern Fleet and not the Kaliningrad-based Baltic Fleet, the threat of Russian undersea sabotage, covert activity, or outright attack is probably greater in the North Atlantic writ large. Nonetheless, given Finland and soon Sweden’s accession to the alliance, NATO should expect to see some corresponding expansion of Russian covert operations aimed at undersea infrastructure in the Baltic Sea. In fact, Russia is already actively mapping undersea infrastructure, and there is evidence that Russian forces are taking greater operational risk in the Baltic and North Seas. It seems safe to conclude that Russia has both the intent and some of the capability to act in this domain, if only as a spoiler.
Aside from the undersea threat, Russia’s anti-access/area-denial capabilities based in the Kaliningrad region have grown formidable over the last several years and include cruise missiles, surface-to-air missiles, and nuclear weapons. Certainly, Russian conventional ground forces have been consumed by the war in Ukraine and there is some evidence that Russia moved ground forces from Kaliningrad to the war zone. Nonetheless, the air, naval, and missile armament of Kaliningrad remains mostly intact, including Su-24, Su-27, and Su-30 ground attack and fighter aircraft capable of launching anti-ship missiles.
Thanks to sanctions against Russia, Moscow will likely have less access to advanced electronic components. This means the quantity, quality, and accuracy of its most advanced long-range fires may diminish over time. However, this does not mean Russian warfighting doctrine will change any time soon or that Russia will give up efforts to circumvent sanctions through trade with third parties. As a result, the West should expect continued Russian reliance on artillery, ballistic and cruise missiles, and advanced air defense capabilities—many of which can outrange and outpace NATO capabilities. Moreover, Russia’s recently released maritime doctrine reinforces the theme of hybrid warfare against the West, including the Baltic region, which Moscow will likely continue to press below the threshold of armed conflict.
Is NATO Prepared to Respond?
The United States and its European allies have limited capabilities and even more limited capacity in the Baltic Sea region to deal with these challenges and the likely threat environment confronting them. In terms of limited capabilities, four areas stand out.
First, undersea domain awareness, particularly surrounding fiber-optic cables and energy connections, remains limited even in the relatively shallow waters of the Baltic Sea.
Second, military mobility challenges throughout Europe continue to impede swift responses in crisis and conflict. Moving large amounts of defense equipment, like armored vehicles or ammunition, across borders in Europe remains hampered by bureaucratic delays and a lack of sufficient European infrastructure prepared for such shipments.
Third, NATO lacks sufficient hardened prepositioned storage sites that are well connected to rail, road, and sea transit options. The United States and some of its European allies have a long history of using hardened storage bunkers for nuclear assets, ammunition, and aircraft in Europe. But in an age of ubiquitous drones and precision hypersonic strike, the alliance must address hardened storage of other critical military supplies, similar to what the U.S. Marine Corps has built in Norway.
Finally, the West lacks the ability to conduct large-scale minesweeping in nonpermissive environments. Mine-hunting and minesweeping are inherently difficult tasks, but they are even more difficult to perform under fire. Russia has, by at least one estimate, as many as 250,000 anti-ship mines, and it has clearly shown its willingness to utilize them in the Black Sea despite the risk to noncombatant ships. If any of these mines are deployed from Kaliningrad or St. Petersburg, allied sea lines of communication could be significantly hampered or cut off completely.
In addition to limited capabilities, the United States and its European allies in the Baltic Sea region are also short on capacity in at least four key ways.
First, allied forces in the Baltic Sea are generally small in quantity and total tonnage. In some cases, allies have sought to replace less capable, older naval platforms with fewer but more capable newer ones. However, other priorities—especially in the land and air domains—have repeatedly pushed naval priorities to the bottom of national acquisition plans. Reflecting generally limited capacity across nearly all the allies in Europe, NATO has long struggled to generate sufficient forces for its Standing Naval Forces.
Second, and relatedly, naval manpower remains limited across the alliance. In nearly all the militaries of the region, navies are the smallest service by manpower. This reflects the fact that armies tend to predominate among continental states, which all of the Baltic Sea littoral states are. It may also reflect the fact that central governments in some Baltic Sea littoral states have essentially ignored their navies for years. Moreover, recent large-scale military operations—Afghanistan chief among them—have placed a premium on robust manning in the land domain.
Third, the alliance lacks sufficient anti-ship coastal artillery. In 2016, NATO aspirant Sweden reinforced Gotland’s defense with a battery of shore-based anti-ship missiles, but Denmark has yet to do the same with regard to the island of Bornholm. Meanwhile, Poland and Latvia await delivery of the mobile anti-ship missile systems they have each ordered. In any case, given the expansion of Russian assets in Kaliningrad over the last few years, the quantity of Western anti-ship assets is probably too low.
Finally, combating Russian capabilities in Kaliningrad requires mass. Not massed humans or massed large platforms—neither of which is pragmatic or likely—but rather, and much more feasibly, massed drone swarms in the air and at sea, enabled by artificial intelligence and guided by onboard inertial systems more immune to Russia’s formidable electronic warfare capabilities. Large quantities of these systems may be necessary to consume enemy ammunition, expose enemy locations, and saturate enemy defenses.
How Should the United States and its European Allies Adapt?
Although cliché and perhaps obvious, most of the challenges outlined above have solutions that begin with additional resourcing at the national level. Increased funding levels are necessary to bring military procurement programs to fruition more quickly and to prevent other, competing priorities from crowding out those that are focused on Baltic Sea security, particularly but not solely in the maritime domain.
Beyond additional resourcing, there are several other ways in which allies can ameliorate capability and capacity shortfalls in their efforts to address the likely security challenges in the Baltic Sea region. For instance, when it comes to military mobility, Sweden can play a critical role by ensuring logistical throughput across the Scandinavian peninsula, connecting civilian road, rail, sea, and air infrastructure, and working to streamline regulations necessary to move military equipment quickly. To test this, NATO allies should exercise the movement of a U.S. or British brigade from Gothenburg on Sweden’s North Sea coast to Visby on the island of Gotland without transiting the Kattegat and Danish Straits. Meanwhile, NATO’s relatively new Joint Support and Enabling Command, based in Ulm, Germany, could be tapped to help identify militarily relevant infrastructure across the region. Because much of the transportation infrastructure that would be necessary for military operations rests in civilian or local government hands, allied military authorities need to communicate now what might be needed in a crisis.
With regard to domain awareness, it made sense that NATO increased patrols in the Baltic Sea following the Baltic Connector incident, even if the damage was probably accidental. But what is necessary over the medium term is a more robust network of linked national monitoring systems to detect the nearby presence of undersea vessels. In February 2023, and partly in response to the sabotage of Nord Stream, NATO created a Critical Undersea Infrastructure Coordination Cell in Brussels, which is intended to improve information sharing and exchange best practices among NATO allies, partners, and the private sector. This is a step in the right direction, but it needs to be operationalized faster.
More recently, in October 2023, NATO’s defense ministers launched the Digital Ocean Vision initiative, which is designed to further enhance maritime situational awareness from seabed to space. Even though the alliance is now developing a roadmap to guide capability development for this initiative, the effort will likely take years to manifest significant progress. In any case, and even though undersea domain awareness is inherently difficult, the alliance needs to move quickly beyond shipboard sensors. Advances in unmanned undersea vehicles and the use of artificial intelligence may make such monitoring on a larger scale more feasible. Allies should embrace a rapid-equipping mindset and consider moving prototypes into the field more quickly.
At the collective level, NATO’s command structure needs further refinement given the Russian threat in the Baltic Sea region. Eventually, after it is properly resourced, the alliance’s Joint Force Command (JFC) at Norfolk will be responsible for alliance defense plans across Scandinavia and Finland. However, this is not ideal. For starters, JFC Norfolk’s area of responsibility is massive—from Florida to Finnmark. Moreover, its location thousands of miles away across the Atlantic will challenge efforts to maintain situational awareness and remain responsive to events unfolding in the Baltic Sea.
Instead, the alliance should repurpose one or more existing headquarters—arguably NATO has too many, especially at the corps level—to create a new, dedicated Baltic/High North joint forces command. Although the Baltic and the High North are distinctive in a variety of ways, there may be synergies gained by viewing and operationalizing the two more holistically. For one thing, the principal threat in each is Russia. Additionally, viewing the Baltic and High North as a single threat environment best leverages the capabilities, capacity, and strategic outlook of Sweden and Finland, which have a foot in both regions. And finally, viewed another way, it is probably not feasible for NATO to craft separate Baltic and High North commands.
Ideally, a new Baltic/High North joint forces command would be based in the United Kingdom and manned mostly by British personnel. This would help to ensure that the JFC is led by one of NATO’s most capable, most expeditionary allies, with a strong naval tradition in particular. It would also fill a gap in terms of leadership among littoral states; Germany might be expected to play a greater role, but this is unlikely.
Additionally, littoral states ought to focus on building so-called plug-and-play interoperability among their military forces instead of multinational force constructs. Much has been made of the plans by Denmark, Finland, Norway, and Sweden to pool their air forces through the development of an integrated command-and-control structure for planning and executing air operations, flexible and sustainable support systems, joint air situational awareness, and joint training and exercise activities. From a tactical perspective, this might make sense—Denmark, Finland, and Norway are all acquiring or have already acquired the F-35 fighter jet, for instance. And politically, given how the four countries are usually aligned on questions of defense and security, it may also seem rational.
Unfortunately, however, pooling and sharing has a poor track record when it comes to implementation. More importantly, the four countries remain sovereign states, and nobody can predict the political decisions their governments may make tomorrow. It is always possible that their political leaders may not agree on the use of military force in some future crisis or conflict. For instance, Finland and Sweden—which seem very aligned today—made very different decisions about intervening in Libya in 2011. Integrating command and control, logistics, and intelligence during peacetime may create interdependencies that could, if one of the integrated states pulls out for political reasons during a crisis or conflict, result in unbridgeable chasms in capability and capacity. One way to mitigate this risk is by building plug-and-play interoperability while maintaining national ability to act, such that the absence of any one actor does not prevent the others from acting individually or collectively.
Beyond NATO, the European Union also has a role to play in strengthening the response to Russia’s threat in the Baltic region, especially given the growing partnership between Moscow and Beijing. That partnership has grown beyond trade in military equipment to include intelligence sharing. This should be of concern to the United States and its European allies because China has a long track record of acquiring militarily relevant infrastructure in Europe, including and especially port facilities, which could easily be leveraged to provide information to Moscow on the comings and goings of various allied military traffic.
Europe has a mixed record when responding to predatory investment by external actors. The EU’s foreign direct investment screening regulation took effect in 2020, but that regulation leaves it to the member states to decide which investments to review, approve, condition, or block. More importantly, under the regulation, member states may maintain their existing screening mechanisms, adopt new ones, or even remain without any such mechanisms—as of early October 2023, only twenty-one of the twenty-seven EU member states have screening mechanisms of any sort. In recent years, much attention has been paid to well-known, national-level cases, such as Chinese investment in the port of Piraeus or the port in Hamburg. What receives far less attention—mostly because central government officials are unaware—is the degree to which Chinese entities invest in and partner with local and regional authorities. This is the soft underbelly of European infrastructure investment vulnerability, which only the EU and its member states can address.
Conclusion
Ultimately, the Baltic Sea is no NATO lake—certainly not while the Kremlin persists in destabilizing the region through hybrid activity and while Russia maintains a formidable, nuclear-armed military capability in Kaliningrad. The United States and its Baltic Sea littoral allies—as well as their mechanisms of collective action such as NATO and the EU—have their work cut out in responding to the likely security challenges posed by Russia over the next several years. Unlike in the land domain, where a window of opportunity will exist in the short run while Russia reconstitutes its depleted ground forces, no such breathing space exists in the maritime, air, cyber, and space domains. This makes the challenge of truly securing the Baltic Sea an urgent issue indeed.
