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The South China Sea is one of the most contested maritime areas in the world. Smaller countries like the Philippines, Vietnam, Malaysia, and Indonesia face increasing pressure from an assertive and militarily powerful People’s Republic of China due to overlapping sovereignty claims and critical trade routes. Beijing’s maritime power projection threatens regional sovereignty and economic rights under the U.N. Convention on the Law of the Sea through its militarization of artificial islands, aggressive maritime activities, and widespread illegal fishing. To address this imbalance, claimant states should adopt asymmetric strategies that improve maritime domain awareness, defend exclusive economic zones, and impose costs on unlawful actions. One such approach is the development of maritime outposts, inspired by the Philippines’ Fort Drum in Manila Bay.

Fort Drum: A Historical Model of Maritime Defense

Fort Drum, built by the United States in the early 20th century, stands as a lasting example of ingenuity in coastal defense from a bygone era. Located at the entrance of Manila Bay, engineers transformed El Fraile Island into a reinforced concrete battleship equipped with 14-inch coastal cannons and designed to withstand heavy bombardment. Although now conceptually outdated, Fort Drum’s resilience during World War II shows the potential of maritime outposts as operational deterrents against gray-zone activities. Accordingly, its legacy provides lessons for modern asymmetric defense in the South China Sea.

Asymmetric warfare aims to impose disproportionate costs on a stronger adversary using dissimilar techniques and capabilities to enhance strengths and mask disadvantages in unexpected ways. Rather than mirroring China’s military build-up, Southeast Asian states can develop layered defenses that leverage geography, low-cost technology, and irregular operations. Recent conflicts highlight the effectiveness of this approach: Ukraine’s innovative use of drone swarms and Azerbaijan’s deployment of loitering munitions in the Second Nagorno-Karabakh War both illustrate how smaller forces can offset conventional disadvantages. Using Fort Drum as an example, these outposts should be seen as methods to maintain presence and complicate adversary maneuvers, rather than static fortresses meant to withstand and repel a direct attack. Fort Drum was carved from an island and reinforced into a concrete battleship, built to withstand direct fire and serve as a lasting deterrent at the entrance to Manila Bay. Today, such maritime outposts can embody similar permanence, signaling sovereignty and deterrence in contested waters.

Applications for Maritime Outposts

Maritime outposts can provide asymmetric advantages by engaging in a contest of perception, access, and legitimacy rather than relying solely on force and finance. They can function as launch and recovery hubs for unmanned aerial, surface, and underwater systems, and as nodes for surveillance and electronic warfare. They can also serve as forward positions for law enforcement and special operations. Instead of building expensive copies of China’s equipment and artificial islands, Southeast Asian nations could discreetly occupy and upgrade man-made and natural terrain into multipurpose nodes. This approach leverages geography and innovation without igniting an expensive arms race. The true strength of these outposts lies more in their ability to complicate Beijing’s calculations for maneuvering and risk tolerance than in their combat power. If claimant states can reliably monitor their waters, publicly expose violations, and respond quickly to gray-zone operations, they can begin to weaken China’s gradual and uncontested expansion strategy.

Such outposts also serve an important symbolic role: Their presence demonstrates sovereignty while their asymmetric capabilities challenge the idea that the South China Sea is China’s to dominate. Fort Drum’s heavily engineered infrastructure, armored turrets, and fortified internal spaces provide a historical comparison. Its resilience against overwhelming force can inspire the design of modern retractable bays and repair facilities to maintain persistence and security just as Fort Drum protected its crew and its shores.

Drone Launch and Recovery

Low-cost aerial and maritime drones can provide persistent intelligence, surveillance, and reconnaissance capabilities, conduct targeted strikes, and overwhelm enemy defenses. By equipping such outposts with launch, recovery, and data uplink capabilities for drones, claimant states can continuously monitor their maritime territories. These outposts can serve as either forward operating bases or part of a network of nodes, discreetly deploying assets into key chokepoints and surveillance zones, thereby reducing risk to personnel while complicating enemy planning.

Just as Fort Drum controlled access to Manila Bay in the early 20th century, the design of new outposts could reflect the importance of sensor and fire-control integration in today’s maritime defense. Modern equivalents could develop by deploying a dense array of electronic and acoustic sensors, thereby mirroring Fort Drum’s role as a sentinel for early warning and deterrence.

Watching and Contesting

The importance of sensor fusion and electronic warfare in modern conflicts is immense, just as the firepower and defenses of Fort Drum were crucial for coastal defense in the early 20th century. Such capabilities not only enhance detection and awareness but also provide a vital offensive edge, as seen in the Second Nagorno-Karabakh War and the ongoing conflict in Ukraine. Utilizing both passive and active sensors in the maritime domain can greatly enhance situational awareness even in degraded and contested environments.

Outposts can be equipped with hydrophones, active radar, and electro-optical/infrared cameras. These tools enable continuous surveillance and data fusion via satellite uplink to mainland fusion centers. Inspired by Ukraine’s Sky Fortress system, a low-cost microphone array for detecting drone activity, countries could deploy acoustic and pressure-based sensing poles above and below the waterline to monitor aerial, surface, and underwater activity with minimal cost and complexity.

The ability to jam, spoof, and deceive enemy systems offers both defensive protection and offensive advantages — modern adaptations of Fort Drum’s armor and coastal guns. Fort Drum’s commanding presence at the entrance of Manila Bay projected strength and sovereignty. Today, maritime outposts can replicate this psychological impact by combining physical presence with cyber and informational tools that amplify state narratives and uncover illegal activities.

Supply and Staging

Fort Drum also served as a secure logistics hub for U.S. forces moving through Manila Bay. Likewise, these outposts can act as supply depots for ships at sea and staging areas for law enforcement and special operations. Maritime outposts could act as resupply points and staging areas, expanding the operational reach of smaller navies and coast guards by providing a more cost-effective alternative to underway replenishment.

The Philippines has already expanded its coast guard and naval presence around contested waters, such as the Second Thomas Shoal, and has been continuously resupplying the Sierra Madre outpost, which faces constant Chinese pressure. Nearby outposts could offer alternative resupply options to these increasingly contested locations by reducing the visibility of sustainment vessels and cutting transit distances. These outposts can also improve security by increasing visit, board, search, and seizure missions, thereby deterring illegal fishing and protecting civilian vessels.

Cyber and Information Operations

Fort Drum demonstrates how well-placed outposts can shape the security structure of a maritime region. Likewise, interoperable maritime outposts across Southeast Asia could create a distributed network that supports regional defense without relying on traditional alliance systems. Here, as with Fort Drum, the perception of resilience can be just as vital as actual strength.

Like Fort Drum’s silhouette at Manila Bay, modern maritime outposts could project resilience through their capabilities and informational influence. When properly manned and equipped, they can reinforce those countries’ narratives by recording, publicizing, and countering illegal activities. The Philippines has already used transparency campaigns to expose Chinese harassment of its vessels, gaining international support. A network of outposts that combines information operations with daily activities would enhance this effect, turning surveillance into strategic leverage. After all, amplifying the success of one’s resistance while exposing an adversary’s misconduct is just as important as achieving those successes, especially when facing a stronger opponent that ignores international laws and norms.

Therefore, these outposts should include a cyber and signals exploitation team by assigning a small, rotating group trained in using commercial tools to scan maritime communications, spoof enemy positioning systems, and monitor illegal fishing activities. In addition to maritime domain awareness, they should help protect civilian vessels to promote adherence to international norms.

Sustainment Considerations

Such outposts could adopt a decentralized operational approach, similar to Ukraine’s “flat war” concept. In this model, rotational detachments should be empowered to act decisively, ensuring adaptability and resilience. Additionally, they should have the independence to acquire, modify, and deploy kinetic and non-kinetic systems in response to rapidly evolving operational needs. This can be supported by on-site 3D printing labs, basic drone assembly workshops, and direct procurement channels to commercial vendors, bypassing complex procurement processes.

Security Framework and Regional Considerations         

The Association of Southeast Asian Nations operates on consensus and non-interference, making collective defense or joint military action under its banner highly unlikely. Instead, claimant states can build and maintain maritime outposts within their own territories and exclusive economic zones while keeping them interoperable through existing partnerships. When it comes to treaty allies such as the Philippines, Japan, Australia, and members of NATO with territory in Asia (most notably France), the United States could provide funding and technical assistance through ongoing maritime security cooperation programs. Bilateral and multilateral exercises that include these outposts would show persistence and cooperation without creating a formal alliance. This decentralized model, grounded in international law, would strengthen deterrence while avoiding charges of militarization.

Any effort to build or adapt structures in contested waters carries diplomatic risks, since even defensive measures may be portrayed as provocative. To reduce that risk, outposts should also serve as fisheries enforcement and environmental monitoring centers, aligning with regional norms and international commitments. Framed in this way, they would appear as cooperative mechanisms, enhancing legitimacy and drawing external support without provoking conflict.

The outcome would be a network of interoperable outposts that operate independently but share a common purpose. Such a system would reflect the principles of gradualism, non-alignment, and strategic autonomy while weaving together a web of maritime sensors and surveillance platforms. This network would bolster deterrence and improve awareness across multiple domains in the South China Sea.

Fixed in Geography, Yet Enhancing Operational Mobility           

Critics will inevitably recall many historical examples of fixed defenses failing against more mobile adversaries. However, these maritime outposts are not solid fortresses designed to repel more powerful and agile opponents. Instead, they should be viewed as maritime patrol bases focused on extending operational reach by gathering intelligence, deterrence, and targeting. They are asymmetric tools intended to enhance the maneuver of maritime forces that are presently poorly matched against Chinese capabilities. These outposts are built for ongoing competition, not a decisive battle. By hosting unmanned systems, sensors, and information operations units, these outposts enable Southeast Asian states to challenge China’s gray-zone activities within a realistic timeframe and without the high costs and extended timelines for acquiring fifth-generation aircraft or expanding blue-water navies. Their strength does not come from confronting force with force but from persistence, visibility, and exposure of illegal actions. Fixed in location but flexible in function, they turn terrain into advantage and presence into influence, demonstrating that such outposts can operate effectively within the competition continuum at sea without the enormous costs of matching force for force.

Conclusion

Fort Drum’s legacy provides a framework for asymmetric operations in contested waters. By transforming maritime geography into resilient outposts that host unmanned systems, sensors, information operations, and security forces, Southeast Asian states can impose costs on Chinese coercion without the high expense of matching its naval buildup ship for ship. Modern Fort Drums do not need to be concrete battleships bristling with guns. They should be flexible nodes that extend security and complicate adversary planning. In today’s contested seas, perception, resilience, and the ability to detect and report are just as crucial as firepower and armor. Reimagined maritime outposts, inspired by Fort Drum’s ingenuity, can form a constellation of defenses that protect sovereignty, enhance maritime domain awareness, and support the rules-based order in the Indo-Pacific.

Ron J. Lienhardt is a Marine Corps infantry officer and Southeast Asia foreign area officer currently serving as the operations officer of the Office of Defense Cooperation at the U.S. Embassy in Kuala Lumpur. Before assuming this role, he served as a rifle company commander and fires and effects coordinator as 1st Battalion 3rd Marines transitioned to become 3rd Littoral Combat Team: the infantry and fires component of the first-ever Marine littoral regiment.

The views expressed in this article are those of the author. They do not represent the views, policies, or positions of the Marine Corps, the Department of Defense, or any part of the U.S. government.

**Please note, as a matter of house style, War on the Rocks will not use a different name for the U.S. Department of Defense until and unless the name is changed by statute by the U.S. Congress.

Image: Midjourney