Introduction

East Asia's maritime security environment is becoming more contested, more complex, and more consequential for the wider international order.[1] As an island nation whose prosperity depends on seaborne trade, Japan relies on secure sea lines of communication across the Western Pacific, the East China Sea, the South China Sea and beyond. Energy imports, food supplies, industrial inputs, and finished products all move through maritime routes that are increasingly exposed to disruption.[2]

Maritime security in East Asia therefore cannot be understood only in terms of major naval battles or wartime convoy protection. It must also be approached comprehensively as a peacetime and gray-zone challenge involving surveillance, law enforcement, infrastructure protection, resilience, and industrial capacity.

The issue is not simply how to defeat an adversary in open conflict, but how to preserve a stable maritime order under conditions of persistent pressure in contested environments. From this perspective, maritime domain awareness, the integration of emerging technologies, the protection of undersea infrastructure, and allied cooperation in maritime industry all become central elements of strategy, and the synchronization of such elements is necessary.

This commentary argues that maritime security in East Asia requires strategic thinking with a comprehensive approach centered on stronger maritime domain awareness, effective integration of emerging technologies, preservation of maritime industrial capacity, and deeper allied coordination in which Japan plays a central role.

Emerging Challenges to Maritime Transportation

Over the past decades, the maritime security environment in East Asia has become increasingly difficult in at least three respects.

First, geopolitical competition has intensified across the Indo-Pacific maritime domain especially since the 2010s. The East China Sea and the South China Sea remain areas of persistent tension, where military modernization, coercive signaling, and competing jurisdictional claims have raised operational pressure on regional states.[3] The cumulative effect is to increase the risk of disruption to commercial navigation and to complicate crisis management at sea.

Second, gray-zone activities have become a defining feature of contemporary maritime competition. These operations remain below the threshold of overt armed conflict, yet they are designed to alter the status quo incrementally through coercion, ambiguity, and persistence.[4] In the maritime domain, use of coast guards, maritime militia, ostensibly civilian vessels, cyber means, and information operations allows pressure to be exerted without immediate escalation. Such methods are especially effective at sea, where attribution can be difficult, territorial disputes are ongoing, and law-enforcement and military jurisdictions often overlap. For Japan and its allies and partners, the implication is straightforward: maritime security must be sustained every day, not only in moments of crisis or war.

Third, the vulnerability of maritime infrastructure has become a growing strategic concern. Undersea communication cables, offshore energy facilities, ports, and logistics hubs form the backbone of contemporary maritime connectivity. Their disruption can generate effects far beyond the immediate physical damage, including consequences for commercial activity, financial transactions, government communications, cyber security and military networks.[5] In East Asia, where dense maritime traffic and geopolitical rivalry intersect, the protection of maritime transportation must now include the protection of the hidden infrastructure that makes transportation, communication, and coordination possible.

An additional danger lies in the vulnerability of international straits and strategic chokepoints. Maritime order depends not only on the safety of shipping in the open ocean, but also on the continued openness of narrow passages through which energy, trade, and data flows must pass. Blocking such straits or attempts to impose political conditions or charges on passage would have consequences far beyond the immediate region. It would challenge not merely commercial efficiency, but the principle of freedom of navigation and rule-based order. Recent tensions surrounding the Strait of Hormuz due to the conflict between US/Israel and Iran are a reminder that the security of maritime transportation is inseparable from the security of strategic chokepoints for the global economy.

Maritime Domain Awareness and Emerging Technologies

In this environment, maritime domain awareness is the indispensable foundation of effective strategy. Maritime domain awareness is more than surveillance in a narrow sense. It is the capacity to detect, identify, track, assess, and share information about activities at sea in ways that support timely political and operational decision-making.[6] In a gray-zone environment, awareness is especially important because ambiguity itself is often used as an instrument of coercion. If states cannot see and understand what is happening in their surrounding waters, they will struggle to respond in a measured and coordinated way, and it will be extremely difficult to exercise sea control. This is true for routine law-enforcement missions, for crisis management, and for deterrence. The side that recognizes a developing situation earlier and interprets it more accurately holds a major strategic advantage.

Emerging technologies can significantly strengthen this foundation. Unmanned aerial, surface, and undersea systems, together with AI-enabled analysis and information-sharing, can expand coverage, enhance persistence, and improve the speed of information collection, analysis, and dissemination.[7] These tools are particularly valuable in a maritime theater as large and complex as East Asia, where wide-area surveillance places heavy demands on crewed platforms alone.

Yet the spread of such technologies also creates new vulnerabilities. The same commercially available systems, digital tools, and autonomous platforms can be used by actors seeking to disrupt maritime order, whether through gray-zone coercion, sabotage, deception, or attacks on critical infrastructure. For that reason, the issue is not simply technological adoption, but competitive adaptation.

States must develop not only new surveillance and response capabilities, but also counter-unmanned systems, electronic warfare, cyber resilience, secure communications, and institutional arrangements that allow coast guards, navies, and other agencies to respond in an integrated manner. Technology matters, but its strategic value ultimately depends on how well it is incorporated into doctrine, training, command and control, and alliance interoperability. In other words, emerging technology is not a one-sided advantage for defenders of maritime order. It is an arena of competition in which resilience, adaptation, and institutional effectiveness will matter as much as acquisition.

The same logic applies to maritime infrastructure protection. Disruptions have social and economic effects both domestically and internationally. Therefore, better awareness is essential not only for tracking vessels and monitoring gray-zone activities, but also for protecting undersea cables, offshore facilities, and port infrastructure. Maritime transportation security today is thus inseparable from infrastructure resilience. The challenge is no longer confined to the visible movement of ships through sea lanes. It also includes the security of the physical and digital systems that enable maritime connectivity.

Industrial Capacity and the Maritime Balance

The regional maritime balance is shaped not only by fleets already deployed, but also by the industrial base that can build, repair, maintain, and replace them over time. No military operation can be sustained without timely and effective logistics.

This is why China's maritime rise must be understood in both military and industrial terms. In addition to modernizing naval, coast guard, and supporting maritime forces, China has developed by far the world's largest commercial shipbuilding industry. Outside analysts have highlighted the strategic implications of its dual-use ecosystem for long-term maritime competition.[8] This industrial scale matters because maritime power depends not only on existing ships, but also on the capacity to sustain competition over time. It is a long-term campaign. Accordingly, long-term planning and execution have developed into huge differences among states. Operations and logistics are the double wheels of maritime security, just like in any other area of security.

For East Asia, this means that maritime transportation security cannot be separated from the regional industrial balance. The ability to escort shipping, sustain patrols, protect chokepoints, and recover from disruption depends in part on whether friendly states retain sufficient maritime industrial capacity of their own. The issue is not simply whether allies can field capable ships today, but whether they can preserve the industrial means to sustain maritime power under prolonged competitive pressure.[9]

This point has special relevance for Japan. Japan still possesses advanced shipbuilding capabilities supported by major firms and highly skilled industrial networks. These capacities contribute not only to commercial shipping, but also to the construction, maintenance, and sustainment of defense-related maritime platforms.

Yet they should not be taken for granted and there is little optimism. Like other advanced industrial states, Japan faces pressure from international competition, investment, labor shortages, and long lead times associated with complex maritime production. Japan's shipbuilding global share was number one in 1956, but long-term decline began in the 1980s. In 2024, Japan only holds 8 percent of global new shipbuilding contract, compared to China's 71 percent and Republic of Korea's 14 percent.[10] Preserving shipbuilding capability therefore requires sustained strategic and policy attention.

This is also where allied cooperation becomes increasingly important. Closer coordination among Japan, the United States, and like-minded countries on shipbuilding, repair, maintenance, supply chains, and maritime technology can strengthen collective resilience. Such cooperation may include industrial dialogue, reciprocal support arrangements, selective co-development, and the alignment of standards in important maritime systems. The strategic value of this approach lies in the way it connects deterrence and resilience, from industries to defense and security in strategic perspectives. A stronger allied maritime industrial base improves peacetime readiness, enhances wartime sustainability, and signals long-term strategic resolve.

Japan's Role in Allied and Partnered Maritime Security

While technology and industrial capacity matter, maritime security ultimately depends on political and operational cooperation among states. Japan occupies a particularly important position in this regard. Geographically, it sits astride critical sea routes linking the Western Pacific, Northeast Asia, and Southeast Asia. Strategically, it is both a frontline state in the regional security environment and a key ally of the United States. When the continental states surrounding Japan want to go out to the Pacific, they must pass through the Japanese archipelago, which stretches more than 3,000 km. Institutionally, it has developed substantial maritime expertise through the Japan Maritime Self-Defense Force (JMSDF) and the Japan Coast Guard (JCG).

The Japan-U.S. alliance remains the cornerstone of regional maritime security. It provides deterrent credibility, operational interoperability, and a framework for shared planning. Within that framework, JMSDF plays an important role in sea control, maritime surveillance, anti-submarine warfare, and the protection of surrounding waters.[11] Yet today's maritime challenges also require wider networks of cooperation beyond the bilateral alliance. Japan has expanded maritime security coordination with Australia, European partners, the Republic of Korea, and Southeast Asian states through joint exercises, capacity-building, port calls, and information-sharing, while recent Japanese policy statement has also emphasized the growing importance of maritime cooperation with Southeast Asia.[12]

NATO is also a part of this picture. An unprecedented delegation of roughly 30 NATO permanent representatives visited Japan in mid-April. NATO's recent efforts to strengthen cooperation with industry on critical undersea infrastructure protection illustrate how these issues increasingly connect the Indo-Pacific and Euro-Atlantic theaters.[13] It showed that engagement with Japan has recently become more operational in character, with discussions focusing on cooperation on maritime security, resilience, and other cross-regional security challenges.[14]

This widening network matters because East Asian maritime stability is no longer a narrowly regional concern. The security of sea lanes, undersea cables, and commercial connectivity in East Asia affects global trade, digital communications, and the broader international order. Cooperation through industries must be counted in these security architectures. Japan is well placed to act as a hub linking regional priorities with wider allied and partner engagement.

Conclusion

This commentary has discussed how maritime security in East Asia can no longer be understood in narrowly naval or purely wartime terms. It must be approached as a broader comprehensive strategic problem that connects persistent gray-zone pressure, the security of strategic chokepoints and infrastructure, technological competition, industrial capacity, and allied cooperation. The central issue is not simply how to prevail in major conflict, but how to preserve a stable maritime order under conditions of continuous pressure and uncertainty.

For Japan and its partners, this means that deterrence, resilience, and cooperation must be treated as part of a single strategic logic. Awareness must be linked to response, technology to adaptation, infrastructure protection to maritime connectivity, and industrial strength to long-term operational endurance. Operations and logistics must go together. In that sense, the future of maritime security in East Asia will depend not only on naval power in the narrow sense, but on the broader capacity of like-minded states to sustain openness, industry, stability, and freedom of navigation over time. The key word is strategic synchronization.

Notes

[1] Government of Japan, National Security Strategy, Tokyo: Cabinet Secretariat, December 16, 2022, pp.2-4. https://www.cas.go.jp/jp/siryou/221216anzenhoshou/nss-e.pdf.
[2] Ministry of Defense of Japan, Defense of Japan 2025, Tokyo: Ministry of Defense, July 2025, pp. 69-76. https://www.mod.go.jp/j/press/wp/wp2025/pdf/DOJ2025_EN_Full.pdf.
[3] Ibid.
[4] Andrew S. Erickson and Ryan D. Martinson, eds., China's Maritime Gray Zone Operations, Annapolis, MD: Naval Institute Press, 2019, pp. 5-7.
[5] Pierre Morcos and Colin Wall, "Invisible and Vital: Undersea Cables and Transatlantic Security," Center for Strategic and International Studies (CSIS), June 11, 2021, https://www.csis.org/analysis/invisible-and-vital-undersea-cables-and-transatlantic-security.
[6] The White House, The National Strategy for Maritime Security, Washington, D.C.: The White House, September 2005, pp.16-17, https://2009-2017.state.gov/documents/organization/255380.pdf.
[7] Government of Japan, National Defense Strategy, Tokyo: Ministry of Defense, December 16, 2022, p.25, https://www.mod.go.jp/j/policy/agenda/guideline/strategy/pdf/strategy_en.pdf. Government of Japan. Defense Buildup Program. Tokyo: Ministry of Defense, December 16, pp. 9, 14-15, https://www.mod.go.jp/j/policy/agenda/guideline/plan/pdf/program_en.pdf.
[8] Matthew P. Funaiole, Brian Hart, and Aidan Powers-Riggs, Ship Wars: Confronting China's Dual-Use Shipbuilding Empire, Washington, DC: Center for Strategic and International Studies, March 11, 2025, pp. 2-6. https://csis-website-prod.s3.amazonaws.com/s3fs-public/2025-03/250311_Funaiole_Ship_Wars.pdf?VersionId=rr_4IH5jXertgzLdS.ke07oFmgWTHnIM.
[9] Ibid.
[10] Sensho Fukami, "National Security and Shipyards Around the World 4- Japan," Ships of the World, No.1059, April 2026, pp.90-91.
[11] Maritime Staff Office, Japan Maritime Self-Defense Force, JMSDF Capstone Doctrine (MDP 1), Japan Maritime Self-Defense Force, 2024, pp. 18-20. https://www.mod.go.jp/msdf/en/about/img/2024doctrine_en.pdf.
[12] Ministry of Foreign Affairs of Japan, New Plan for a "Free and Open Indo-Pacific (FOIP)," Tokyo: Ministry of Foreign Affairs, March 20, 2023, pp. 1-2. https://www.mofa.go.jp/files/100477739.pdf.
[13] NATO, "NATO Strengthens Cooperation with Industry to Protect Critical Undersea Infrastructure," May 27, 2025, https://www.nato.int/en/news-and-events/articles/news/2025/05/26/nato-strengthens-cooperation-with-industry-to-protect-critical-undersea-infrastructure.
[14] "Eastward bound: Largest-ever NATO envoy delegation to visit Japan amid China, Trump concerns," The Japan Times, April 13, 2026, https://www.japantimes.co.jp/news/2026/04/13/japan/nato-japan-ambassadors-focus/.

Views expressed or implied in this article are solely those of the author. They must not be construed as representing the views and positions of RIPS or any other organizations.