The global strategic environment is ripe for technology-driven great power competition once more. Russia’s war in Ukraine and pursuit of novel nuclear weapon delivery vehicles, coupled with China’s expanding nuclear arsenal and capabilities, mean the United States must assess its capabilities and posture in more theaters simultaneously than ever before. Among them, contested maritime spaces could be the most pivotal, acting as chokepoints for military movement, trade, and anti-access/area denial (A2/AD) measures. Changing technology and heightened great power tensions are making control of strategic maritime spaces, such as the Greenland-Iceland-UK (GIUK) Gap, more important and more challenging than ever before. To combat it, NATO can leverage its incomparable joint forces and embrace a new array of technologies to safeguard control, avoiding ambiguity and harnessing a transparent posture. “Mind the Gap” During the height of the Cold War, the GIUK Gap was a critical naval chokepoint in the North Atlantic. Its deep waters represented the only outlet into the Atlantic Ocean for the Soviet Northern Fleet, essential for affording Moscow the ability to hit the North American continent with submarine-launched ballistic missiles (SLBM). “Closing” the gap thus became a NATO priority; sonar surveillance systems were established across the gap to listen for Soviet submarines, while naval deployments sought to establish operational control of the seas in the event the conflict turned hot. The strategic importance of the GIUK Gap diminished as the range of Soviet SLBMs increased, meaning submarines no longer had to get as close to their targets. This capability allowed Moscow to avoid increased western monitoring that might render their nuclear weapons-capable submarines (SSBNs) vulnerable to detection. Instead, these submarines retreated into bastions, highly defended waters close to their homebase on the Kola Peninsula in Russia’s north. As the Cold War ended and the age of peace dividends began, NATO anti-submarine warfare (ASW) capabilities in the Gap atrophied; in 1989, the United States alone had a force of 80 submarines and 122 principal surface combatants in the Atlantic. In 2022, the United States had 35 and 60, respectively. Today, conventional wisdom argues that Russia’s revanchist foreign policy and calculated nuclear modernization mean the GIUK Gap has regained significance despite Moscow’s intercontinental standoff capabilities. Fears about Russian A2/AD “bubbles,” its ability to influence the European theater with capable long-range missiles from bastions, the threat of hybrid operations, and new deployments in the High North necessitate a fresh approach to the waters in and beyond the Gap. This paper builds on that wisdom, identifying the technical, strategic, and political implications of a NATO A2/AD push in the region. Why the Gap matters to Moscow While the Gap doesn’t feature prominently in written Russian doctrine, it clearly “imposes itself on Russian naval thinking as a potential barrier to operations.” The security of Russia’s prized Northern Fleet depends on effective A2/AD and control in the High North. Russian SSBNs in the Arctic are the Navy’s raison d’être, and they are undergoing a spate of modernization that will take Moscow’s submarines far into the 21st century. Eventually, six new Borei-A type submarines will be assigned to the Fleet to replace the aging Delta IV class, while a new next-generation sub, Arktur, could replace older Borei models after 2037. Each Borei submarine can carry 16 Bulava SLBMs, which can carry up to six warheads each – though this number is probably less under New START constraints. Despite the range of these weapons, effective A2/AD around the GIUK Gap is key for Moscow if it is to keep its most prized bases out of the range of U.S. Tomahawk missiles and give them a safe haven from which to hold Europe and beyond at risk. Freedom in the north also enables Russia to utilize hybrid tactics that are challenging to combat. Despite the poor performance of the Russian Navy in the Black Sea and the rebuilding that must be undertaken, Moscow’s Northern Fleet remains a challenge for NATO in the north. Putin’s long-term ambition for a blue water navy appears steadfast. While a Russian break through the Gap is not immediately likely, weakening Moscow’s A2/AD dominance in the GIUK neighborhood for long-term control ought to be a top priority for the Alliance. Reprioritizing the “forgotten flank” Amidst an atrophied northern force and other strategic priorities, NATO’s presence in the High North and around the Gap remains patchwork. This, despite the 2022 Strategic Concept noting that Russia’s High North “capability to disrupt Allied reinforcements and freedom of navigation across the North Atlantic is a strategic challenge to the Alliance.” NATO needs to embrace new technology to tighten its own A2/AD stranglehold in the key GIUK Gap neighborhood, leveraging initiatives in long-standing member states and capitalizing on the momentum of welcoming two new Arctic countries to the Alliance. NATO’s priority is slowly turning to the once-forgotten flank. The U.S. Navy re-established the 2nd Fleet in 2018, bolstering forward presence, while other NATO allies have modernized and closed intelligence, surveillance and reconnaissance (ISR) gaps, including with a new radar array in the Faroe Islands. Norway, a key player in mitigating unimpeded Russian A2/AD, signed a defense cooperation agreement with Washington in 2022, enabling U.S. assets to maintain closer proximity to Russian bastions than before, while presence has been strengthened in Iceland too. The United Kingdom will play a pivotal role across the GIUK Gap, though its ASW capabilities are slimmer than before. Royal Air Force P-8A Maritime Patrol Aircraft deployments and a proposed new generation of ASW frigates have bolstered joint force efforts and exercises like Dynamic Mongoose for this purpose, but eyes will be on next year’s defense review and whether it will embrace the challenge with new focused procurement, including on unmanned systems. Some analysts have suggested that the Russian challenge in the High North cannot be solved by focusing on the GIUK Gap alone. While a full embrace of open-ocean ASW is ideal, capacity and technology constraints are limiting factors. In the interim, a hardened barrier of A2/AD assets around the Gap and outward from Norway’s territorial waters will not only strengthen NATO’s High North capabilities and protection of key operating lanes from Russian influence, but also provide a training ground for a host of new technologies relevant to the wider region and other global strategic chokepoints. Testing ground Despite an operational need, NATO is still facing the new renewed challenge of the GIUK Gap on the back foot. While increased deployments and investments in conventional technologies are key to plug gaps, allies should look to the success of Ukraine in the Black Sea and deepen investment in novel unmanned systems to conduct ASW missions, support deployments, and bolster deterrence. Specific systems remain nascent at scale, not helped by the limitations in funding compared to conventional naval assets. However, an array of new technologies have the potential to bolster ASW operations and deepen NATO capabilities. Extra-large uncrewed underwater vehicles (XLUUVs) like Boeing’s Orca and large unmanned surface and undersea vehicles (LUSVs) can greatly enhance underwater surveillance and ASW capabilities, altering the balance of power in submarine detection and tracking. That capability is multiplied if drones are deployed in swarms to track and detect adversary submarines. A vast network of these vehicles, highly interconnected and deploying advanced sensing systems, could reshape the balance of the submarine cat-and-mouse game and improve resilience in the event of escalation. Since this new generation of ASW technologies, and networking them together between domains and allies, poses a “daunting” technical challenge, every effort should be made to scale these technologies into Gap-specific drills like Dynamic Mongoose, providing a live testing ground for their abilities closer to Russian patrols and bastions. The imperative to pair these systems with capable SSNs should also underscore the importance of ongoing British and American submarine procurement efforts. No single new technological advancement will be a “game changer” by itself. As adversaries jostle for supremacy in such contested spaces, they must be alert and adaptable to the fallacy of the last move. But the GIUK Gap provides a true and appropriate testing ground for rapidly integrating these long experimental technologies to patch conventional gaps. In deepening the makings of a diverse NATO-coordinated A2/AD zone around and north of the GIUK Gap, Allies can get ahead of Russia’s Northern Fleet modernization while it is relatively preoccupied in Ukraine. Its war with Kyiv might deplete resources, but it does not detract from the importance of the chokepoint and access to the Atlantic for Moscow. Moreover, growing Chinese ambitions in the High North create an added layer of importance to establishing such operations. Imperatives for strategists and policymakers Such an approach has implications for strategists and military planners. First, as emerging technology blurs the lines between traditional domains, controlling spaces like the Gap in the modern age increasingly requires multi-domain integration – in other words, coordination across air, land, surface, subsurface, cyber, and space. This increases the number of domains of competition in which conflict is possible. Multi-domain integration of forces can help counter and increase resilience against Russian A2/AD, though an effective calibrated force posture is not without complex technological challenges. Further, the United States and its allies must ingrain strategic flexibility in their own postures and force composition. While Russian naval forces still utilize the bastion model in the High North, any hypothetical attempt to ‘break’ out the Gap requires an array of capabilities to counter. Allied navies must be able to rapidly call on capable ASW forces and leverage new technology to squeeze Russian movement. Such an approach also requires new operational concepts, with missions ranging from passive monitoring in open oceans to a return to active area denial and operating in confined, contested waters. Russian reliance on gray zone or hybrid operations in the region further complicate NATO mission requirements and response options. This flexibility has policy implications too. Policymakers must consider how long-term investments in the new Columbia-class and Virginia-class programs can remain relevant in the rapidly changing technological environment. Upgrades to new Virginias that add the Virginia Payload Module (VPM) afford new builds more firepower and flexibility, but the fact remains these boats were designed with different threat profiles in mind. The return of the Harpoon anti-ship missile affords the U.S. Navy a diversified capability in contested maritime space. This is not to say that the prevalence of submarines is coming to an end. However, allocating resources to maintain the levels of strategic flexibility required, including through investment in a plethora of new unmanned and autonomous technologies, is key and will not come cheap. Finally, the challenges of the GIUK Gap demonstrate the importance of allied cooperation and the role that smaller operators can play in greater strategic chess games. The United States is not the only player concerned with a contested High North – other adversaries like China are likely to seek the benefits of new transpolar routes opened by melting ice sheets. Meanwhile, allies including the three nations that make up the Gap – Denmark (via Greenland and the Faroe Islands), Iceland, and the United Kingdom – plus others in the region like Norway, are all likely to be affected by Moscow’s growing presence and interruptions. These shared interests provide an opportunity for resource pooling, burden sharing, and joint technology development. Ensuring interoperability of forces, especially where nascent technology is concerned, as well as coordinated decision-making and defense planning make this new environment a challenging one but offer real buy-in and free up U.S. assets for other theaters. Conclusion The relevance of the GIUK Gap is back. And while contested strategic chokepoints like the Gap come with new strategic and technological challenges that might endanger critical forces operating there, it is a relevance that NATO must fully embrace while Russia is moderately hamstrung in Ukraine. Prioritizing joint programs, investing in novel unmanned ISR and ASW capabilities, and strengthening its own A2/AD capabilities can help the Alliance regulate the Gap and deny Russia access even in turbulent times.