Recently, The Newport Manual on the Law of Naval Warfare was published as volume 101 of International Law Studies. Scholars from Australia, Germany, India, Japan, the United Kingdom and the United States produced the Newport Manual as a restatement of the law of naval warfare from the perspective of the state practice of major maritime powers. The best guide to how the law of naval warfare may be applied in a future conflict is to revisit what states have done in the past and capture those practices and lessons to inform future planning and operations. The Newport Manual is divided into 12 chapters and is a pithy analysis of the principles and rules governing conflict at sea for commanders and their staffs, and officials, and scholars.

The Newport Manual was produced to prepare for and deter war at sea, and to facilitate combined operations if conflict occurs. There is an increased sense that naval warfare is likely and the risk is increasing, yet commanders and their staffs, as well as officials and scholars, heretofore lacked a single, authoritative reference. From the Black Sea to the Taiwan Strait and East and South China Seas, the threat of naval war is growing. Any armed conflict scenario in these regions is likely to involve an armed clash at sea between the United States and a rival naval power, potentially drawing NATO or its members in the West or Japan and possibly Australia, Korea, or even strategic partners such as India in the East. The United States and its allies and partners deter aggression by enhancing interoperability for combined operations and conducting planning and exercises. Understanding and applying the law of naval warfare is a key element of this effort, but until now, the requisite principles and rules governing the law of naval warfare are spread among treaties, customary law, individual state approaches reflected in national military manuals, and scholarly works. There is little coherence to these references, impeding effective combined operations. The Newport Manual explains the commonalities and differences in the law of naval warfare among maritime allies and partners to enhance operability.

The Newport Manual captures and clarifies the range of state practice. States make international law, and the law of naval warfare involves recognition of four bodies of overlapping rules: the law of the sea, as reflected in the United Nations Convention on the Law of the Sea, the law of armed conflict or international humanitarian law, including the law of blockade, the law of prize capture, and the law of maritime neutrality. The considerable divergence and intersection in these bodies of law highlights areas of agreement and disagreement among states and scholars. In response, sometimes scholars have attempted to distill the law into doctrinaire lists of “rules,” but these invariably reflect the bias of the authors in the face of the reality of divergent state practice. Rather than attempt to artificially box states in through approaches favored by one state or group over the other, the Newport Manual reflects the range of authoritative state practice and acknowledges and respects the variations among maritime powers during conflict at sea. That is, the authors focus on accurately restating the law of naval warfare as it has and would apply during armed conflict (jus in bello), rather than evaluating interesting scholarly theories or offering aspirational or progressive notions that seek to change or transform the law lex ferenda. If there is a bias in the Newport Manual, it is toward the actual practice of major maritime powers during naval warfare.

The United States and its treaty allies and partner nations in Europe and East Asia are likely to fight in a coalition, yet until now there has not been a single suitable guide for such operations. The United States has chapters on the law of naval warfare in the 2022 Commander’s Handbook on the Law of Naval Operations and the 2016 Department of Defense Law of War Manual, but these reflect only U.S. views and positions. Likewise, other national military manuals, including those of Australia, the Netherlands, France, Germany, and the United Kingdom, reflect only one country’s views and therefore are not a helpful guide to coalition naval warfare, in which allies and partners must understand and appreciate how each constituent force contributes to combined operations in accordance with their distinct approach to law and operations. Unlike all other official or scholarly works on the subject, the Newport Manual acknowledges that powerful and influential maritime powers have genuine differences in how they interpret and apply the law of naval warfare. States reasonably disagree, for example, on the scope and application of rules of naval warfare, such as targeting the enemy’s warfighting or war sustaining effort.

There is a practical imperative toward a single, authoritative guide on the law of naval warfare. This is not an academic exercise. The Newport Manual reflects lex lata state practice in the law of naval warfare as it has been practiced or is being exercised in training by major maritime powers. While writing in their personal capacities, the authors have decades of experience serving as legal adviser in the naval forces of Australia, Germany, India, Japan, the United Kingdom, and the United States, and teaching in their military schoolhouses. These experiences have informed the authors’ work in publishing a manual useful to Navy, Marine, and Coast Guard in time of war. Further, the Newport Manual was strengthened by peer reviewers from Australia, Denmark, Israel, Japan, the Philippines, Switzerland, the United Kingdom, and the United States.

This gives rise to a related issue: sovereign states operating in the international system are the principal actors who make international law. While the Statute of the International Court of Justice also recognizes that “writings of the publicists” may influence international law, it is axiomatic that treaties and customary law, as informed by state practice, form most international law and are the most authoritative aspects of the law. The Newport Manual leverages these “hard” sources of law. And, while it does not reject writings of the publicists altogether, it tends to stick to only those titanic figures who have stood the test of time – L. Oppenheim and D. P. O’Connell, e.g., and in the field of the law of naval warfare, Robert W. Tucker, and Newport Manual author Wolff Heintschel von Heinegg.

Why produce the Newport Manual now?

The Newport Manual is the most recent restatement on the law of naval warfare since the U.S. Chief of Naval Operations published Naval Warfare Publication 10-2 in 1955 (and reissued in 1974). The law of naval warfare is also mentioned in several chapters of the 2022 Commander’s Handbook on the Law of Naval Operations, continuously published since 1986. Just like their counterparts in other countries, however, these publications reflect only the U.S. view. One multi-national effort to represent the body of law across states is the San Remo Manual on International Law Applicable to Armed Conflicts at Sea (SRM), but is outdated, asserts some “rules” that are not grounded in the law, and does not capture the range of authoritative state practice.

Since its publication in 1994, the SRM has been a welcome resource about the law of naval warfare, but its shortcomings are increasingly evident and unsuited for today. The SRM emerged from a series of meetings considering the law of naval warfare during the Iraq-Iran “Tanker War,” and it was not completed and published until 1994. The publication is very much a product of its time, when actual combat at sea was less likely than it had been at any time before or since. By 1994, the Soviet Union had collapsed, its navy a decaying relic. One of the greatest issues of the day was the legality of Russia’s disposal of nuclear submarines in the oceans deep. That same year the United States participated in the first Russia-U.S. military exercise since World War II, Cooperation from the Sea. The combined operation occurred south of Vladivostok and involved amphibious U.S. forces aiding a Russian humanitarian assistance mission in the Khasan region of Primorye, where the borders of Russia, China, and North Korea converge. The Russian Navy (and indeed the port city of Vladivostok) was in apocalyptic disrepair. Only one warship, Admiral Vinogradov, could get underway. The other surface ships were in progressive states of inoperable decrepitude. Major systems were offline, with heads not working and crews sleeping on urine-soaked mattresses lying on the steel deck. As a legal adviser during the exercise, I recall U.S. Sailors and Marines felt great sorrow and pity for the Russians and embarrassment at our ascendant position and how low the Soviet Navy had fallen. Great power conflict at sea was a distant memory.

Since then, the SRM has been a reference for many of the issues in the law of naval warfare. But arising in the era of the “peace dividend” in the aftermath of the Cold War, its mistaken confluence of the peacetime law of the sea and the law of naval warfare introduces elements of marine environmental protection and marine resource conservation that do not reflect international law. For example, paragraph 34 of the SRM purports to sensitize operational commanders to exercise “due regard” for coastal state fisheries, a prescription that applies in peacetime but not during naval warfare. The law of naval warfare is lex specialis, and to the extent that the law of the sea is inconsistent with it, it does not apply during armed conflict at sea. Indeed, during the discussions at the UN General Assembly in the late-1960s to negotiate a law of the sea, security issues were peeled away and addressed separately, with this parallel effort resulting in the Seabed Arms Control Treaty.  While the SRM is laudable for educating generations of officers and scholars, including me, these errors and others have unwittingly worked their way into some national manuals and risk introducing theoretical mistakes into real world operational planning when the chips are down. This dynamic recalls the quote by Yogi Berra, the late professional baseball player: “In theory there is no difference between theory and practice – in practice there is.”

Furthermore, the passage of time since 1994 begs the question on certain key legal issues that are not addressed at all in the SRM, such as the legal status of unmanned ships during armed conflict at sea. While scholars debate whether the theory of sovereign immunity fits unmanned ships, in the real-world states are already deploying them. The United States, China, and other maritime powers are building fleets of unmanned warships and other autonomous systems. The U.S. Navy’s Task Force 59, for example, employs a drone fleet to exercise maritime domain awareness over Iran in the Persian Gulf. This pioneering effort is now being replicated in the U.S. Fourth Fleet in the Caribbean and Central and South America. Meanwhile, the Chief of Naval Operations plans to build some 150 large, unmanned warships and submarines to augment the manned surface navy. The Newport Manual clarifies that these unmanned fighting vessels are protected by sovereign immunity and enjoy peacetime navigational rights and freedoms and belligerent rights during armed conflict.

The Newport Manual presents the law of naval warfare based on state practice – one that is more current and more accurate than any alternative, in how states have incorporated the law of naval warfare into their operations.

IMAGE: Ships participating in Exercise Baltic Operations 2023 steam in formation through the Baltic Sea, June 4, 2023. (Photo by Navy Petty Officer 2nd Class Mario Coto/U.S. Navy)