The Indo-Pacific Is Being Built by Coast Guards

Across Asia’s contested waters, white-hulled vessels are doing the daily work of sovereignty, deterrence and corridor control.

The Indo-Pacific is usually described through the language of navies, missiles, bases and alliances. Aircraft carriers pass through contested waters. Fighter aircraft cross air defence identification zones. Submarines patrol beneath the first island chain. War games imagine a Taiwan contingency, a blockade, or a clash in the South China Sea. Yet much of the region’s daily contest is being shaped by vessels that are not formally warships.

They are coast guard cutters, fisheries enforcement vessels, maritime police ships and patrol boats. They are the white hulls that sit between civilian administration and military force. They look less escalatory than destroyers, but they can still enforce claims, challenge shipping, escort resupply missions, block access, seize fishing vessels, fire water cannons and force rivals to respond. Across the Indo-Pacific, these vessels are doing the slow, repetitive and politically sensitive work of remaking maritime order.

The latest dispute east of Taiwan illustrates the point. Chinese coast guard patrols in waters around Taiwan have been framed by Beijing as law-enforcement activity designed to protect sovereignty and maritime rights. Taiwan has rejected that position, accusing Chinese vessels of harassing merchant shipping, questioning vessels about their origins and destinations, and attempting to assert jurisdiction where Taipei says Beijing has none.¹ The argument was not simply about the movement of several patrol ships. It was about who has the authority to police the sea.

That distinction matters. When a coast guard vessel asks a merchant ship where it is going, where it came from and under whose authority it is operating, it is doing more than checking paperwork. It is performing sovereignty. It is making a political claim through a law-enforcement act. In disputed waters, this is often the central function of the coast guard: to make a state’s map visible at sea without immediately crossing the threshold into open naval confrontation.

This is why coast guards have become so important to the Indo-Pacific. They are less dramatic than naval task forces, but more usable. They allow states to maintain pressure every day, not just during crises. They can occupy space, normalise patrols, challenge rivals and complicate response options. A navy appearing in the same waters may look like escalation. A coast guard vessel can say it is simply enforcing domestic law.

The result is a regional order increasingly shaped below the threshold of war.

The white hull as a sovereignty tool

The traditional view of coast guards was relatively straightforward. They saved lives at sea, enforced fisheries rules, protected ports, responded to pollution, intercepted smugglers and supported maritime safety. Those functions remain essential. But in East and Southeast Asia, coast guards have acquired a much sharper strategic role.

Lyle Morris described this shift as the rise of coast guards as “blunt defenders of sovereignty.”² His formulation captures the transformation well. Coast guards are no longer only maritime law-enforcement bodies dealing with civilian actors. They have become frontline state instruments in territorial disputes. They are used to demonstrate presence, assert administrative control and contest rival claims, often in waters where the deployment of naval vessels would carry greater escalatory risk.

This does not mean coast guards have become navies. It means the boundary between law enforcement and national defence has blurred. A coast guard vessel may still operate under civilian or constabulary authority, but in contested waters its mission can become strategic. It may be enforcing a fisheries regulation, but it may also be reinforcing a sovereignty claim. It may be escorting civilian vessels, but it may also be testing another state’s willingness to intervene. It may be conducting a patrol, but the patrol itself can become the message.

China has made the most consequential use of this model. In the South China Sea, the China Coast Guard operates alongside maritime militia and, in the background, the People’s Liberation Army Navy. The layering matters. Maritime militia and fishing vessels can create presence and ambiguity. Coast guard cutters provide the visible law-enforcement face. Naval forces remain further back, available as a deterrent and potential escalation backstop. This allows Beijing to apply pressure while complicating the response of states such as the Philippines, Vietnam and Malaysia.³

The strength of the model is not that it avoids coercion. It is that it packages coercion as enforcement. When a coast guard blocks access to a reef or shoal, fires a water cannon, or shadows a resupply vessel, it can be presented as a policing action rather than a military operation. That creates a dilemma for the opposing state. Respond with its own coast guard and risk being physically overmatched. Send the navy and risk appearing to militarise the incident. Ask the United States or another ally for direct support and risk making the confrontation part of a larger geopolitical contest.

This is the grey zone at sea. It is not peace, but it is not conventional war. It is the space where legal language, vessel size, hull colour, rules of engagement and political messaging all become instruments of power.

Taiwan and the jurisdiction contest

The Taiwan case shows how this model can move beyond the South China Sea. Chinese coast guard activity east of Taiwan is not only a Taiwan issue. It is part of a broader maritime trend in which Beijing uses law-enforcement language to stretch its operational presence and normalise jurisdictional claims.

Taiwan’s concern is straightforward. If Chinese patrols become routine, and if those patrols begin questioning merchant vessels or claiming authority over routes around the island, then a new maritime reality may emerge through repetition. No blockade needs to be declared. No missile needs to be fired. The first step is to establish the appearance of administrative authority.

That is why the language of law enforcement is so powerful. “Patrols” sound routine. “Maritime traffic enforcement” sounds technical. “Sovereignty and maritime rights” sound legalistic. But in contested waters, these terms can conceal a larger strategic ambition. The aim may be to make foreign and commercial vessels behave as if Chinese authority already exists.

This is especially important for Taiwan because its security is not only a military question. It is a corridor question. Taiwan sits at the centre of a dense network of shipping, energy flows, undersea cables, semiconductor supply chains and air-sea connectivity. A full invasion would be catastrophic, but lower-level maritime pressure could still affect insurance, routing, commercial confidence and crisis calculations.

The danger is incrementalism. A patrol becomes normal. A warning becomes routine. A challenge to shipping becomes expected. A coast guard presence becomes part of the operating environment. Over time, the political map changes not through a single dramatic event, but through the accumulation of maritime habits.

For Power & Corridors, this is the central point. The Indo-Pacific’s strategic map is not only being redrawn by military deployments. It is also being redrawn by who can police the routes through which commerce moves.

The Philippines as the frontline case

If Taiwan shows how coast guard activity can test jurisdiction, the Philippines shows how it can become a sustained confrontation.

Manila faces one of the most difficult maritime security problems in the region. It must defend its rights in the South China Sea against a much larger Chinese coast guard, a large maritime militia and the shadow of Chinese naval power. Philippine resupply missions, patrols and presence operations around contested features have repeatedly faced Chinese pressure, including blocking, ramming, water cannons and other grey-zone tactics.⁴

The imbalance is not simply numerical. It is structural. China can keep larger vessels at sea for longer. It can replace damaged ships more easily. It can rotate coast guard and militia assets through contested areas. It can escalate or de-escalate pressure while keeping the confrontation below the level of formal war. The Philippines, by contrast, must preserve limited naval and air assets for the possibility of escalation, while relying heavily on its coast guard to sustain daily presence.

This makes the Philippine Coast Guard strategically important but operationally stretched. A 2025 study of the PCG’s training programme found strengths in emergency response, maritime law-enforcement awareness and environmental protection awareness, but also recurring challenges involving funding, facilities, instructors, training periods, supplies and policy implementation.⁵ That matters because coast guard competition is not only about ships. It is about crews, doctrine, endurance, logistics, communications and confidence under pressure.

The Philippines has made important gains. It has become more transparent in publicising Chinese actions at sea. It has deepened cooperation with the United States, Japan and Australia. It has used its coast guard to turn grey-zone incidents into visible international issues rather than private coercion. But the capacity gap remains severe. The more China relies on coast guard and militia pressure, the more Manila must invest in the practical infrastructure of maritime law enforcement.

This is where the “defending without provoking” argument becomes relevant. The United States faces a genuine policy dilemma. If Washington takes too frontal a role in Philippine operations, it risks turning every confrontation into a direct US-China test. If it stays too far back, Manila may be left exposed to coercion. The balance lies in enabling the Philippines to lead, while strengthening its maritime domain awareness, coast guard capacity, logistics, legal position and resilience.⁶

That is a difficult balance, but it is the right frame. The answer to grey-zone pressure is not always a larger warship. Often, it is a better-trained coast guard, clearer rules, stronger communications, better public documentation, allied capacity building and the ability to stay at sea longer than the coercer expects.

Japan’s alternative model

China is not the only state shaping the Indo-Pacific through coast guards. Japan has built one of the region’s most capable coast guard systems, and its approach offers a different model of maritime influence.

The Japan Coast Guard has long been central to Tokyo’s maritime security. Its role has expanded from domestic safety and order at sea to international cooperation, capacity building and support for Japan’s Free and Open Indo-Pacific vision. Japan’s coast guard diplomacy is built around rule of law, freedom of navigation, maritime domain awareness and support for regional partners.⁷

This is not altruism alone. It is strategy. Japan understands that the Indo-Pacific’s maritime order depends not only on the Japanese Maritime Self-Defence Force, but also on the ability of Southeast Asian and Pacific states to police their own waters. If weaker states cannot monitor illegal fishing, respond to coercion, control their exclusive economic zones or maintain maritime law-enforcement presence, then larger powers can exploit the vacuum.

Japan’s approach is therefore corridor-building in a security sense. Ports, railways and trade agreements are one part of its regional strategy. Maritime law enforcement is another. A state that can police its waters is harder to coerce. A region with capable coast guards is harder to dominate through ambiguity.

This is why coast guard cooperation has become part of the broader Indo-Pacific architecture. Training programmes, exercises, vessel transfers, information sharing and maritime domain awareness networks may look technical. In reality, they help determine whether smaller and middle powers can preserve agency in contested seas.

Japan’s model also shows that coast guards do not have to be instruments of coercion. They can be instruments of order. The same type of vessel can either enforce excessive claims or defend legal rights. The difference lies in the political purpose behind the patrol.

The US Coast Guard’s quiet strategic role

The United States has also recognised the coast guard dimension of Indo-Pacific competition. The US Coast Guard’s Western Pacific Region Resourcing Strategy presents the region as directly tied to US strategic maritime interests, partner capacity, fisheries law enforcement, transnational crime and economic security.⁸ This is an important shift in emphasis. It recognises that the Indo-Pacific is not only a theatre for naval deterrence, but also a space where maritime governance affects power.

The US Coast Guard is useful because it offers a different kind of American presence. In many regional contexts, it is less politically sensitive than the US Navy. It can train, advise and operate with partner coast guards in ways that feel more aligned with local maritime law-enforcement needs. It can work on illegal, unreported and unregulated fishing, search and rescue, port security, boarding procedures, pollution response and maritime domain awareness. These are practical issues for coastal states, but they also build strategic resilience.

Recent US-Philippine maritime cooperative activity shows how this can work. US and Philippine coast guard and military units conducted exercises involving maritime domain awareness, manoeuvring and visit, board, search and seizure procedures in the Philippines’ exclusive economic zone.⁹ Such activity is not just symbolic. It improves interoperability, builds confidence and supports Manila’s ability to operate in contested waters.

Still, the US Coast Guard has limits. It is globally stretched, has domestic obligations and requires resources to sustain presence in the Western Pacific. Its role cannot substitute for allied strategy or local capacity. But it can fill an important space between diplomacy and naval deterrence. In a region where too much military signalling can be dangerous and too little support can invite coercion, the coast guard is a useful instrument.

Small states and normative sea power

The rise of coast guards should not be understood only through China, the United States, Japan and the Philippines. Smaller maritime states also matter. They may lack large fleets, but they are not passive actors in the Indo-Pacific order. They use law, diplomacy, partnerships, public communication and maritime governance to defend their interests.

This is where the idea of “normative sea power” is useful.¹⁰ Not every state can compete through ship numbers or tonnage. Some compete by shaping the rules, strengthening maritime institutions, documenting violations and framing disputes through international law. For smaller states, the coast guard can become part of a wider diplomatic and legal strategy. It is the agency that turns abstract maritime rights into practical presence.

That matters in Southeast Asia. Singapore, Brunei, Malaysia, Vietnam, Indonesia, the Philippines and Timor-Leste all operate within a maritime region where legal rights, economic dependence, fisheries, energy exploration and great-power pressure overlap. Their coast guards and maritime agencies do not simply patrol domestic waters. They help preserve sovereign agency in a region where larger powers can otherwise impose realities at sea.

Normative sea power is not soft in the sense of being weak. It is a recognition that maritime order depends on more than naval force. A state that can document an incident, invoke UNCLOS, communicate clearly, coordinate with partners and sustain legal presence at sea can raise the political cost of coercion. It may not defeat a larger coast guard physically, but it can prevent coercion from becoming invisible or accepted.

This gives the article’s central argument a more balanced shape. China uses coast guards to expand authority and normalise claims. Japan and the United States use coast guard partnerships to build capacity and reinforce maritime order. Smaller states use coast guards, law and public diplomacy to defend their room for manoeuvre. The Indo-Pacific is therefore not only being policed by coercive powers. It is also being defended by states using law-enforcement presence as a form of maritime statecraft.

Coast guards and the new corridor map

The rise of coast guards matters because maritime disputes are not isolated legal arguments over rocks, reefs and lines on a map. They sit across trade corridors.

The South China Sea links Northeast Asia, Southeast Asia, the Indian Ocean and the wider global economy. Taiwan sits near critical shipping lanes, energy routes, undersea infrastructure and advanced manufacturing supply chains. The waters around Japan, the Philippines and the first island chain are not peripheral. They are part of the operating system of global trade.

If coast guard patrols begin shaping where vessels feel safe operating, then they are already affecting commercial geography. If repeated challenges make insurers more cautious, they are affecting risk pricing. If resupply routes require escorts, they are affecting logistics. If maritime militia and coast guard vessels can create uncertainty around access, then they are shaping the corridor without closing it.

This is the real significance of the white hull. It can alter behaviour before war begins. It can make shipping companies, fishermen, energy firms and governments adjust to a new normal. It can create facts at sea slowly enough to avoid crisis, but persistently enough to change the balance of control.

For smaller states, this creates a strategic challenge. They cannot match China ship for ship. But they can invest in presence, transparency, partnerships and legal clarity. They can document incidents, strengthen coast guard professionalism, improve communications, and build coalitions around maritime law. They can also make coercion more costly by ensuring that grey-zone activity is exposed rather than absorbed quietly.

For middle powers, the coast guard era creates an opportunity. Japan, Australia, India and others can support maritime capacity without always sending warships. They can help build the institutions that allow coastal states to defend their waters in politically sustainable ways. This is not a substitute for defence alliances, but it is an essential layer beneath them.

For the United States, the lesson is restraint plus capacity. Washington should avoid making every coast guard incident a direct great-power confrontation. But it should also avoid the opposite mistake: treating maritime law enforcement as a secondary issue. In the Indo-Pacific, the coast guard is no longer secondary. It is where sovereignty, deterrence and commerce meet.

Below war, but not below strategy

The Indo-Pacific is often described as a region preparing for possible war. That is true, but incomplete. It is also a region being shaped every day by actions below war.

A Chinese coast guard patrol east of Taiwan, a Philippine resupply mission near Second Thomas Shoal, a Japanese capacity-building programme in Southeast Asia, a US Coast Guard deployment in the Western Pacific, a maritime militia swarm near a disputed feature, a boarding exercise in the Sulu Sea: these are not separate stories. They are part of the same strategic pattern.

The ships may not be destroyers, but the stakes are naval. The missions may be called law enforcement, but the effects are geopolitical. The incidents may look local, but the consequences touch trade corridors, alliance credibility and the regional balance of power.

The Indo-Pacific is not only being militarised. It is being policed into a new shape. The vessels doing much of that work fly coast guard colours, but their impact reaches far beyond maritime safety. They decide where patrols become presence, where presence becomes control, and where control begins to alter the movement of trade, energy and power across Asia’s most contested waters.

The future of the Indo-Pacific may still depend on navies. But the present is being built by coast guards.

Notes

1. Reuters, “China, Taiwan Spar over Legality of Coast Guard Patrols East of Island,” June 10, 2026; Reuters, “Taiwan Says It Won’t Tolerate Chinese Patrols, Vows Expulsions,” June 11, 2026.
2. Lyle J. Morris, “Blunt Defenders of Sovereignty: The Rise of Coast Guards in East and Southeast Asia,” Naval War College Review 70, no. 2, Spring 2017.
3. Andrew S. Erickson, ed., Maritime Gray Zone Operations: Challenges and Countermeasures in the Indo-Pacific, Routledge, 2023.
4. Shang-Su Wu, “The Philippines’ Security in the Face of China’s Rising Threats,” Parameters 54, no. 4, Winter 2024-25.
5. Abdurasa T. Tomi, “The Philippine Coast Guards’ Training Program: The Prospect for an Institutionalized Human Resource Development Agenda,” Journal of Interdisciplinary Perspectives 3, no. 3, March 2025.
6. Sarang Shidore, “Defending Without Provoking: The United States and the Philippines in the South China Sea,” Quincy Institute for Responsible Statecraft, February 12, 2025.
7. Kentaro Furuya, “The Japan Coast Guard’s Role in Realizing a Free and Open Indo-Pacific,” Pacific Forum PacNet 4, January 12, 2023.
8. United States Coast Guard, Western Pacific Region Resourcing Strategy: Report to Congress, December 9, 2025.
9. Commander, Task Force 71/Destroyer Squadron 15, “U.S. and Philippine Coast Guards Conduct Maritime Cooperative Activity,” May 21, 2025.
10. Blue Security, issue paper on maritime security and normative sea power, 2026.