The Neglected Domain

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This series—featuring scholars from the Futures Lab, the International Security Program, and across CSIS—explores emerging challenges and opportunities that NATO is likely to confront after its 75th anniversary.

In the future, NATO will need to field a larger, more capable fleet that can deny Russia the ability to hold member states at risk in the maritime domain and degrade Moscow’s ability to conduct long-range cruise missile strikes.

After the collapse of the Soviet Union in the early 1990s, the maritime focus of the North Atlantic Treaty Organization (NATO) began to pivot from major combat operations to regional maritime security operations. This less-demanding warfighting mission slowly devolved into a series of minor external operations of the alliance. By the time Russia reintroduced NATO to the challenges of major combat operations in 2022, most NATO navies had already lost the ability to fight a major combat operation.

NATO’s maritime capacity shrunk significantly following the collapse of the Soviet Union, and most of the new entrants to NATO after 1994 brought very few maritime assets of value. Exacerbating this decline, the combat operations that NATO militaries entered into in Afghanistan (2001) and Iraq (2003) had significant ground and air components but very limited maritime missions. As a result, NATO maritime commanders and planners began to focus on smaller regional maritime security operations in the southern flank of NATO to include Africa and the Middle East. These operations—such as Operation Sharp Guard, Active Endeavour, Sea Guardian, and Open Shield—required fewer, less capable ships than traditional maritime combat operations. With few exceptions, NATO member navies shrunk down to the size and priority of the new maritime missions.

The illegal Russian invasion of Ukraine in 2022 and subsequent Russian naval operations have demonstrated the breadth of Russian naval capabilities. At the same time, the war exposed challenges traditional naval powers face keeping up with emerging technology at sea. In a future crisis, Russia could create strategic challenges for NATO in the Mediterranean, the Baltic Sea, the High North, and even off the coast of Florida, but it cannot maintain sea control in the Black Sea against a Ukrainian navy that fights without any ships. Today, as NATO planners begin to grapple with this new aggressive Russian maritime challenge, planners no longer have the capabilities or capacities they would want to build and implement the maritime plans they need.

As NATO looks to close this gap and build the naval capacity it needs, a few investment areas are clear. Some investments require restoring traditional military capabilities, and others involve responding to the new maritime battlefield demonstrated in the Black Sea over the past two years.

First, NATO needs more maritime assets—specifically, warships. Not all 32 countries can, or should, field traditional navies equipped with multi-mission warships, but for those traditional naval powers, investments are desperately needed. The NATO navies will need a sufficient capacity of warships and maritime patrol aircraft to ensure multi-mission assets are present throughout all the areas Russia can exploit. The U.S. Navy is overtly the largest warship contributor, and to make this contribution more effective, it should expedite the stationing of two additional ships in Rota, Spain, which would effectively increase the total to six AEGIS destroyers. 

Second, undersea warfare capabilities need expanded investment—despite Russia’s budgetary challenges, the Russian navy has consistently developed, constructed, and deployed highly capable attack and guided missile submarines that can threaten NATO operations and logistics. While construction of submarines is not a realistic goal for most member states, the littoral NATO nations can invest in less expensive assets such as ocean surveillance ships and maritime patrol and surveillance aircraft. As the technology develops, littoral states can also invest in undersea warfare drones.

Third, the Russian invasion of Ukraine has demonstrated Russia’s commitment to persistent ballistic and cruise missile employment. Ironically, Ukraine’s cruise missile attacks against Russian Black Sea fleet assets have demonstrated the vulnerability of ships to these types of attacks. This has been reinforced by the cruise and ballistic missile and drone attacks by Houthi rebels against merchant shipping in the Red Sea beginning in October 2023. A significant number of NATO member warships lack the weapons control systems and affecters needed to deal with a high-density air threat environment. Additionally, no NATO navy has a good solution for either the very high-end risks (hypersonic maneuvering cruise missiles) or the low-end risks (drones). 

Fourth, one of the big takeaways from two years of maritime combat in the Black Sea is Ukraine’s ability to use land-based anti-ship cruise missiles (ASCMs—domestically manufactured Neptune and ally-provided Harpoon), as well as unmanned autonomous surface vessels (USVs), to prevent Russia from asserting sea control in the Black Sea. This has removed the threat of a Russian amphibious assault (which would stretch Ukrainian defenses even thinner) and allowed for Ukraine to slip its grain shipments out through the Dardanelles and into the Mediterranean. Numerous smaller NATO littoral states, especially those on the Baltic Sea, may not be able to afford destroyers and frigates, but they can procure land-based ASCMs and USVs.

Fifth, there is the need to invest in enhancing and protecting maritime logistics. This applies to the traditional aspect of maritime shipping and ports as well as the increasingly important issue of protecting critical undersea infrastructures such as fiber-optic cables. At the 2023 Vilnius summit, NATO leaders agreed to establish NATO’s Maritime Centre for the Security of Critical Undersea Infrastructure in the United Kingdom in order to increase the alliance’s situational awareness about these threats.

After nearly thirty years of contraction and stagnation, the maritime mission set is finally a growth area within NATO. There are a number of key areas for investment: warship capacity, undersea warfare, integrated air and missile defense, land-based strike weapons, and logistics. Not all 32 member nations need to invest in all five of these areas, but there should be some opportunities for every nation that has a littoral presence.

RADM (ret) Mark Montgomery (U.S. Navy) serves a senior fellow at the Foundation for the Defense of Democracy and directs CSC 2.0, an initiative that works to implement the recommendations of the congressionally mandated Cyberspace Solarium Commission, where he served as executive director. Benjamin Jensen is a senior fellow for Futures Lab in the International Security Program at the Center for Strategic and International Studies in Washington, D.C., and the Petersen Chair of Emerging Technology and professor of strategic studies at the Marine Corps University School of Advanced Warfighting.

Mark Montgomery

Senior Fellow, Foundation for the Defense of Democracy
Benjamin Jensen
Senior Fellow, Futures Lab, International Security Program