The Return of the GIUK Gap: A New Pillar of European Security

US Air Force. (2005). Aerial picture of Thule Air Base. Wikipedia.

On January 6, 2026, White House comments indicating renewed interest in Greenland brought Arctic and Northern Atlantic security back into discussion (Reuters, 2026). While much of the public debate has focused on U.S.-Danish relations, there has also been a revival of interest in the Greenland-Iceland-United Kingdom (GIUK) Gap. The GIUK gap is a maritime and air corridor central to the North Atlantic Treaty Organisation (NATO)’s collective defense planning, owing to its strategic naval position connecting the Arctic Ocean to the North Atlantic. As relations with Russia remain adversarial and NATO’s northern flank continues to expand, this gap has now become a focal point of security tensions. 

Context

Three developments have influenced the strategic importance of the GIUK gap. First, since the onset of the war in Ukraine, there has been an increased reliance on transatlantic reinforcement, pushing Nordic states to reorient defense planning around NATO structures and alliances. As a result, Finland and Sweden abandoned their stance of military non-alignment, leading to Finland’s accession to NATO in 2023 and Sweden’s accession in 2024 (Wieslander & Adamson, 2024). Together, their membership transformed the Baltic Sea into a NATO-controlled maritime space, limiting Russia’s access beyond Kaliningrad, and leaving it dependent on its Northern Fleet. Lastly, climate change-driven ice melting in the Arctic has facilitated greater accessibility for the operation of naval vessels, a shift reflected by Russia’s growing presence in the region (Lynch,  Norchi and Li, 2022). 

Greenland’s Role in Transatlantic Defense

“GIUK Gap” map. Originally published by the U.S. Central Intelligence Agency (public domain), hosted on Wikimedia Commons.

Greenland’s strategic importance lies not in its symbolic significance but in its operational utility. Its location at the northern gateway between North America and Europe enables continuous surveillance of transatlantic sea and air routes, with radars used for early-warning signals and submarine detection. The GIUK gap constitutes one of the few viable routes for large-scale military reinforcement from the US. Its integrity determines whether or not industrial and military capacity can transit the Atlantic unimpeded. Therefore, protection of the corridor, and Greenland as its integral part, is essential for sustaining collective self-defence and maintaining credibility. 

For surveillance and early warning systems, the Pituffik Space Base, established in 1951 under a mutual defence agreement with Denmark to counter Soviet missiles launched over the Arctic, remains the only active US base in Greenland. The base hosts the 12th Space Warning Squadron, which operates and supports Missile Warning and Missile Defence missions (United States Space Force, n.d). Most importantly, the squadron employs the ballistic missile radar weapon system, which detects intercontinental ballistic missile (ICBM) threats and submarine-launched ballistic missile (SLBM) threats (United States Space Force, n.d.). The base is thus critical for transmitting early-warning signals to U.S. and NATO commands and for supporting missile-defence cueing to improve response times. Pituffik is a part of the Space Delta 4 missile warning enterprise (the United States Missile Warning Unit), and is directly linked to send data to other early-warning radars, such as RAF Fylingdales in the U.K, which is the European node of the Ballistic Missile Early Warning System (BMEWS), and is optimised to detect missile trajectories directed toward Europe (Tanghe, 2025). 

The base employs a phased array radar – specifically, an Upgraded Early Warning Radar (UEWR) – which, unlike traditional radars, has no mechanically moving antennas. Instead, the antenna is electronically steered within milliseconds, allowing it to shift focus instantaneously and respond considerably faster (Buckley Space Force Base, n.d). Since the radar is two-sided, its combined total coverage spans a 240-degree field of view over the Arctic and North Atlantic (Buckley Space Force, n.d). It is for these reasons that Greenland constitutes a core pillar of NATO’s defensive security.

Russian Northern Fleet as a Challenge

For NATO, the Russian Northern Fleet represents Moscow’s most capable instrument of power projection in the North Atlantic and poses a potential obstacle to Europe’s reinforcement. Based on the Kola Peninsula, the Northern Fleet hosts Russia’s most advanced nuclear-powered submarines, particularly its ballistic missile submarines that operate from bases such as Severomorsk (Conley, Melino, and Alterman, 2020). Their positioning can underpin Russia’s sea-based nuclear deterrent while applying pressure to NATO’s northern flank (Conley, Melino, and Alterman, 2020). 

The GIUK gap is crucial for Russian forces, as it is effectively the only channel through which they must pass to enter the wider Atlantic. At the same time, it is crucial for NATO’s defense of European reinforcement lines, including surface logistics and undersea communications. Russia is continuously seeking to modernise its submarine forces on the Kola Peninsula, and to enhance its A2/AD (anti-access/area-denial) capabilities, according to a recent CSIS report (Ward, 2024). Its strategic planning in the region places clear emphasis on upgrading bases and layering maritime and air defences. Research by Chatham House highlights Moscow’s efforts to rebuild Soviet-era military infrastructure, modernise its North Sea Fleet, and expand military bases along the Arctic Littoral. These endeavours are intended to secure lines of approach towards the GIUK corridor (Boulègue, 2019). Additionally, reports submitted to the U.K. Parliament corroborate Russian submarines operating in the North Atlantic and along the Nordic/U.K coastlines at rates not seen in two decades, prompting calls for urgent enhancements to anti-submarine efforts. The CSIS report similarly points out that NATO allies’ anti-submarine warfare (ASW) capabilities are faltering and will continue to do so unless the North Atlantic is once again prioritised (UK Parliament Committee, 2017).

Therefore, through a European NATO lens, these dynamics position Greenland and the GIUK gap not as peripheral concerns, but as vital gatekeepers. Ensuring the integrity of its sea and airspace is essential to safeguard the alliance’s ability to reinforce European forces and protect Atlantic sea lines of communication. 

Implications on European Security

Europe’s security is still shaped predominantly by its reliance on reinforcement from its transatlantic allies. Although there is a rise in defence spending among EU allies – estimated at €381 billion in 2025, an 11% increase compared to 2024 – prominent capability gaps persist (Council of the European Union, 2026). From 2020 to 2024, approximately two-thirds of military arms imported by European NATO members were produced in the United States (Pfeifer, S., Tauschinski, J., & Clover, C., 2025). Consistently, U.S. contributions made up 64% of NATO defence expenditure in 2024, while Europe and Canada together accounted for the remaining 36% (Reuters, 2025). Even with all NATO members projected to meet the 2% of GDP defence spending target in 2025, the United States’ overall contribution remains structurally higher in absolute terms.

Washington continues to provide the majority of arms, defence systems, nuclear deterrence, and advanced command-and-control systems on which the alliance depends, and these capabilities could be compromised if the security of the GIUK corridor is not fully ensured. While many European nations are expanding their defence capacities, high-end capabilities such as ballistic missile defence systems and nuclear forces remain dependent on cross-Atlantic allied reinforcement. Should critical early-warning nodes not be protected, NATO’s ability to reinforce Europe rapidly and credibly would be weakened. 

Conclusion

Greenland and the GIUK gap are indeed strategic pillars upon which the security of Europe and the credibility of NATO rest. At a time of heightened political tension and competition, control of this gap directly shapes NATO’s ability to deter aggression and monitor all security risks. The unique geographic position enables continuous monitoring of transatlantic sea and air routes and provides early warning of missile and security threats through Pituffuk’s advanced technology and capabilities. As Russia’s Northern Fleet increasingly relies on the corridor as its primary access to the Atlantic, the gap becomes ever more critical for ensuring the secure movement of allied forces, reinforcements, and logistics between North America and Europe.

This article represents the views of contributors to STEAR's online digital publication, and not those of STEAR, which takes no institutional positions.

---

REFRENCES

Bayer, L. (2025, April 25). NATO’s Rutte calls for ‘quantum leap’ as Europe boosts defence investment. Reuters. https://www.reuters.com/world/europe/natos-rutte-calls-quantum-leap-europe-boosts-defence-investment-2025-04-24/

Boulègue, M. (2019). Russia’s military posture in the Arctic: Managing hard power in a “low tension” environment (Chatham House Research Paper). The Royal Institute of International Affairs. https://www.chathamhouse.org/sites/default/files/2019-06-27-Russias-Military-Posture-Arctic.pdf

Conley, H. A., Melino, M., & Alterman, J. B. (2020, March 26). The Ice Curtain: Russia’s Arctic military presence. Center for Strategic and International Studies. https://www.csis.org/analysis/ice-curtain-russias-arctic-military-presence

Council of the European Union. (2026, January 7). EU defence in numbers. Consilium – European Union. https://www.consilium.europa.eu/en/policies/defence-numbers/

Holland, S., Mason, J., & Erickson, B. (2026, January 7). Trump discussing how to acquire Greenland; US military always an option, White House says. Reuters. https://www.reuters.com/world/trump-advisers-discussing-options-acquiring-greenland-us-military-is-always-an-2026-01-06/

Lynch, A. H., Norchi, C. H., & Li, X. (2022). The interaction of ice and law in Arctic marine accessibility. Proceedings of the National Academy of Sciences of the United States of America, 119(26), e2202720119. https://doi.org/10.1073/pnas.2202720119

Pfeifer, S., Tauschinski, J., & Clover, C. (2025, March 9). Two-thirds of arms imports to Nato countries in Europe come from US. Financial Times. https://www.ft.com/content/d3214157-639b-4743-ab29-9af662d47ec5

Tanghe, M. (2025, April 14). Going, going . . .? The US base network in Europe. Center for European Policy Analysis. https://cepa.org/article/going-going-the-us-base-network-in-europe/

U.S. Central Intelligence Agency. (n.d.). GIUK Gap map [Public domain image]. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:GIUK_gap.png

United States Space Force. (n.d.). 12th Space Warning Squadron. Buckley Space Force Base Fact Sheets. https://www.buckley.spaceforce.mil/About-Us/Fact-Sheets/Article/2291701/12th-space-warning-squadron/

United States Space Force. (n.d.). Pituffik Space Base, Greenland. Peterson and Schriever Space Force Base. https://www.petersonschriever.spaceforce.mil/pituffik-sb-greenland/

US Air Force. (2005). Aerial picture of Thule Air Base. Wikipedia. https://en.wikipedia.org/wiki/Pituffik_Space_Base

Ward, S. (2024, September 12). The GIUK Gap: A new age of A2/AD in contested strategic maritime spaces. CSIS Nuclear Network. https://nuclearnetwork.csis.org/the-giuk-gap-a-new-age-of-a2-ad-in-contested-strategic-maritime-spaces/

Wieslander, A., & Adamson, E. (2024, November 5). How Sweden and Finland’s membership in NATO affects the High North. Atlantic Council. https://www.atlanticcouncil.org/in-depth-research-reports/issue-brief/how-sweden-and-finlands-membership-in-nato-affects-the-high-north/