In August, at Finland’s request, the Swedish government deployed fighter aircraft and a warship to help patrol Finland’s eastern airspace and the Gulf of Finland against Russian air incursions and drones straying from Ukrainian operations. Critically, the Swedish assets involved were placed under Finnish command and followed Finnish rules of engagement. It was the latest example of how Finland and Sweden, the two newest additions to NATO, have made qualitative leaps in defense coordination.

The Nordic countries have expanded regional collaboration significantly in the past four years. Between them, Denmark, Finland, Iceland, Norway, and Sweden now boast a new long-term defense strategy, a cross-border transit area, frequent joint exercises, and unprecedented levels of command integration.

In effect, these governments are forming their own regional deterrence cluster: a like-minded group of states deepening military cooperation to strengthen deterrence and, if required, ensure NATO’s broader collective defense.

The Nordic model offers a glimpse of the adaptive solutions that may sustain NATO through uncertain times. Moscow’s appetite for risk is growing; its military buildup and escalating attacks on European infrastructure suggest that Russia constitutes a long-term threat to the alliance. At the same time, the Trump administration is pushing its European allies to take primary responsibility for the continent’s defense. Europeans must therefore deter a more dangerous Russia with less help.

To strengthen their deterrence and defense capabilities, member states along NATO’s extended frontline—and in the Baltic and Black Sea regions, in particular—should build their own regional clusters and foster a strong latticework of bilateral and “minilateral” partnerships with their neighbors. Regionalization remains a taboo subject among most of the alliance’s political leadership; NATO is, after all, a collective defense alliance founded on indivisible security. But regional efforts at the military level will both make NATO more effective and advance the United States’ vision of a more European NATO.

Nordic-style deterrence clusters are thus a win-win. Yet in its erratic, occasionally aggressive approach to Greenland and the North Atlantic, Washington has risked undercutting the very allies that are delivering what it wants. The United States should use the recently signed Greenland deal as a reset to embrace Nordic defense efforts and create incentives for other allies to follow suit.

Marriage of Convenience Nordic defense collaboration took its current institutional form in 2009, when recession-era budgetary constraints pushed the region’s five countries to rethink their defense commitments. Finland and Sweden joined NATO members Denmark, Iceland, and Norway in establishing the Nordic Defense Cooperation, primarily in hopes of cutting procurement costs. NORDEFCO boasted some early wins, including cross-border air force training in the uncongested airspace of northern Finland, Norway, and Sweden. But because NORDEFCO spanned NATO members and non-allied states, bureaucratic hurdles and a lenient threat environment quickly sapped momentum from joint procurement.

Only after Russia’s 2014 invasion of Ukraine did some Nordic countries begin to see cooperation as a security imperative, not just a way to save money. Finland and Sweden launched a no-limits military partnership that included joint wartime planning. And Norway, despite maintaining its NATO-first approach, gradually embraced operational cooperation with its two non-NATO neighbors in times of crisis. By 2020, when the countries signed a trilateral statement of intent, they were conducting intensive joint exercises, sharing intelligence on common threats, and discussing their national defense plans with an eye toward coordinated crisis response.

Any remaining limits on Nordic military cooperation evaporated once Finland and Sweden joined NATO following Russia’s full-scale invasion of Ukraine, in 2022. The region’s five countries agreed that Moscow posed an urgent security threat to themselves and to Europe as a whole. Even Denmark, which was previously reticent about regional collaboration, warmed to collective defense efforts. In 2023, it joined Finland, Norway, and Sweden in developing the Nordic Airpower Concept, which will give them the ability to fight as one force with their combined 250 advanced fighter aircraft.

Denmark has also pledged to contribute personnel to the Swedish-led Forward Land Forces Finland, the NATO battle group that rotates between northern Finland and Sweden. When Denmark served as chair of NORDEFCO in 2024, the five governments also signed NORDEFCO Vision 2030, which outlines their ambition for joint operations that are aligned with both national and NATO defense interests. To support the logistical underpinnings of land force cooperation, the initiative established a seamless, borderless Nordic military mobility corridor.

A division of labor is now emerging: Finland commands regional land operations, Norway hosts the regional headquarters for air operations, and Sweden is becoming the logistics hub and transit area for joint military operations in northern Europe. Denmark, for its part, hosts a regional headquarters for special operations.

The Nordic deterrence cluster also functions smoothly within NATO’s collective defense framework. Larger NATO allies—including France, Germany, the United Kingdom, and the United States—routinely operate and exercise in the Nordic space alongside their regional partners and fill capability gaps in areas such as intelligence, reconnaissance, and surveillance. The result is an increase in defense capabilities in NATO’s Joint Operations Area Northwest, which covers the North Atlantic and includes vital sea-lanes, critical undersea infrastructure, and the Arctic and Nordic regions bordering Russian strategic hot spots. Imitation Game Deterrence clusters could well be the future of NATO’s frontline posture.

In addition to NATO’s Joint Operations Area Northwest, NATO has two more regional plans—Center, covering the Baltic states and central Europe, and Southeast, covering Turkey and the Balkans—each with its own operations area and command center network. Governments in these two regions should follow the Nordic example and take the initiative to strengthen their own minilateral ties within the NATO framework.

An obvious starting point is the southeastern Baltic Sea, which sits at the heart of NATO’s Joint Operations Area Center. Although the Baltic states have a shared vulnerability to Russian encroachment, defense cooperation has been modest since they joined NATO, with Estonia, Latvia, and Lithuania preferring to rely on extraregional patrons such as the United States. Recent moves, however, suggest that regional collaboration is gathering pace: Estonia and Latvia have jointly procured the IRIS-T air defense system, and all three countries are coordinating their HIMARS rocket systems and building the Baltic Defense Line, a fortification project designed to channel, delay, and block a Russian ground invasion.

But Baltic cooperation would benefit from a more comprehensive minilateral layer resembling NORDEFCO. In practice, this could mean coordinating national defense plans, conducting joint exercises, and sharing missile stocks for air defense systems. It could also entail merging HIMARS launchers for joint fires capability, better integrating national contributions to the Baltic Defense Line, and jointly operating uncrewed vessels to monitor the sea and underwater infrastructure. The aim would be to enable three militaries to fight together as seamlessly as possible, generating a combined power greater than the sum of its parts.

Such a format, if realized, should also involve Poland—an emerging European military powerhouse that currently plays a limited role in Baltic defense. Although Warsaw maintains a relatively robust defense partnership with Lithuania, involving joint exercises and working groups, the two neighbors have previously failed to establish a joint exercise area in the Suwalki Gap, a key strategic corridor and vulnerable supply line connecting the Baltic states to continental Europe.

A stronger minilateral framework would create a standing process for joint planning and consultation that could resolve the local objections and divergent strategic priorities that have dogged previous negotiations over the gap. In extreme circumstances, subregional clusters would offer a hedge.

Within such a framework, Warsaw could reinforce regional defense by connecting its East Shield—Poland’s own program of fortifications, barriers, and surveillance systems along its borders with Russia and Belarus—with the Baltic Defense Line and by contributing ground-based air defenses to NATO’s Baltic Air Policing mission. The fundamental aim should be to strengthen Poland’s role as a leading security provider in the Baltic region alongside Germany, which is permanently stationing a brigade in Lithuania.

The other frontline arena that would most benefit from a deterrence cluster is the Black Sea region, which sits within NATO’s Joint Operations Area Southeast. Bulgaria, Romania, and Turkey have struggled to cooperate because of divergent assessments of the threat posed by Russia. Building minilateral latticework here is clearly harder than in the Nordic or Baltic Sea areas. But in a more European NATO, the rest of the alliance would expect Black Sea allies to contribute more to collective defense, and the conditions for doing so are improving.

The most promising domain for expanded minilateral cooperation is maritime. In July 2024, Bulgaria, Romania, and Turkey launched a joint mine-clearing operation, which led to the establishment of a joint mission to protect energy infrastructure, telecommunications networks, and undersea pipelines owned and operated by the three allies. This embryonic naval force could be developed further to cover more ambitious contingencies in the Black Sea, from sea surveillance to the protection of territorial integrity, as the Finnish-Swedish naval task force does in the Baltic Sea.

Air forces are another potentially fruitful area for Nordic-style collaboration, especially as regional militaries grow their capabilities. Bulgaria awaits its F-16s, Romania is set to acquire F-35s, and Turkey, already a potent air power, is seeking readmission to the F-35 program. In the late 2000s, the Nordic air forces began weekly cross-border training, paving the way for today’s cooperation. More frequent exercises among the Black Sea allies would be a logical first step toward enhancing interoperability.

For the Nordics, reaching today’s level of collaboration took more than 15 years. Other frontline regions cannot afford to wait that long. Russia may emerge from the war in Ukraine more capable and less risk averse. Tighter subregional cooperation would not only benefit the security of exposed allies on the frontline by enhancing their capacity to respond together. It would also make NATO’s frontline posture more effective, deterring Russian encroachment deeper into Europe—an aim that allies farther from the frontline should share.

Moreover, by strengthening the minilateral latticework, countries close to Russia would enhance their capacity to act together before NATO acted collectively. In extreme circumstances, if the alliance was paralyzed, subregional clusters would offer a hedge, enabling frontline allies to respond together.

A Dog in the Fight The United States, too, has a vested interest in the development of deterrence clusters across NATO’s eastern borderlands. U.S. officials have articulated a vision for “NATO 3.0,” a rebalanced alliance in which Europeans lead their own conventional defense and the United States plays a supporting role, providing extended nuclear deterrence and a few other capabilities.

If the Europeans are to assume primary responsibility for their conventional defense, subregional cooperation arrangements—with high interoperability, joint procurement, planning and command capacity, cross-border mobility, and even certain divisions of labor—will be paramount.

Nordic defense cooperation represents the most mature version of such efforts, and the Nordic states have already demonstrated their readiness to work with the United States on Russian-related security threats. Finland and Norway, for instance, have directed their intelligence capabilities toward monitoring what happens on the Russian side of their borders, and Finland lets U.S. signals-intelligence aircraft use its airspace to monitor the Kola Peninsula, where the majority of Russia’s nuclear second-strike capability is concentrated. By preventing Russian dominance in the broader North Atlantic, Nordic cooperation has also advanced the 2025 U.S. National Security Strategy objective of maintaining—in cooperation with allies and partners—favorable balances of power in the world’s key regions.

There is every reason for Washington to treat the Nordic states as exemplary allies and endorse their advancements in regional cooperation. And yet the Trump administration’s approach to the region has been at best incoherent. On the one hand, U.S. officials have commended Nordic efforts to bolster defense spending—Denmark, Finland, Norway, and Sweden are all above or on track to reach three percent of GDP by 2029 and are committed to reaching the Hague target of five percent of GDP by 2035. On the other, U.S. President Donald Trump has repeatedly mused about taking over Greenland, a nightmare scenario for the Nordics that would pit their mutual solidarity against their respective relationships with the United States.

The Greenland agreement that Washington, Copenhagen, and Nuuk signed in September should encourage the Trump administration to play a larger, more constructive role in Arctic security. So far, Washington has treated defense spending as the key enabler of NATO 3.0. But a European-led alliance also needs allies that can use their growing capabilities as efficiently and seamlessly as possible. If the United States were to encourage and back Nordic-style minilateral latticework in other critical subregions, it would empower a more competent, capable, and commanding NATO 3.0.