By, With, and Through at the Second Thomas Shoal


If war breaks out in the Indo-Pacific, it will not be over Taiwan but over the atolls and shoals dotting the South China Sea. At least, that’s the argument the Philippine ambassador to Washington has made, calling these sovereignty disputes, particularly between China and the Philippines, the region’s “real flashpoint.”

Today, the South China Sea facilitates $3.4 trillion of global trade and contains untold amounts of fossil fuels and fish. China covets these routes, resources, and riches. It also wants dominion over these “near seas” to curtail American military operations near its coastal economic and military hubs. Over the past decade, China has added teeth to its claims of control by greenlighting a destabilizing maritime insurgency to coerce Southeast Asian nations into relinquishing their maritime rights.

Nowhere in the South China Sea seems as ripe for conflict as Second Thomas Shoal. China claims “indisputable sovereignty” over the feature, even though it is tucked well within the Philippine exclusive economic zone. The Philippines defends its claim by stationing a rotational contingent of marines aboard the Sierra Madre, a World War II landing craft beached atop the shoal, to monitor Chinese encroachments. In recent years, Chinese military and paramilitary forces have escalated tensions by harassing and blocking Philippine units during rotation and reprovision missions, particularly when China accuses Philippine ships of carrying construction supplies to reinforce the Sierra Madre’s structural integrity.

In a clear signal to China, the Biden administration and the Department of Defense have pledged “ironclad support” for the Philippines in the event of an armed attack. Officials stress that the 1951 U.S.-Philippine Mutual Defense Treaty extends to the Sierra Madre and nearby Philippine units.

Yet Chinese strategists may reckon that by operating “just short” of America’s redlines, eroding Philippine resolve, and raising the risk of conflict, they can make American and Philippine leaders wonder whether it is worth going to war over a shoal. Chinese security experts surmise that Washington’s commitment may waver when faced with a great war over a small reef, as it did during the 2012 Scarborough Shoal standoff.

Fortunately, the United States and its allies have the tools to prevent China from wresting control of Second Thomas Shoal — and the South China Sea — before bullets fly, but it will demand a sea change. Upholding Philippine sovereignty demands more than rhetoric and signals. It requires tangible security support and methodical planning. Providing Philippine forces with training, resources, public support, and operational expertise will empower the Philippine defense of Second Thomas Shoal and compel Beijing to reassess its aggressive campaign. Robust American backing — short of direct military intervention — will prompt Beijing to ponder its own question: Is it worth going to war over a shoal?



From Stilts to Strongholds

In 1994, China seized Mischief Reef, a feature 13 nautical miles northwest of Second Thomas Shoal, and built a small structure on stilts to supposedly give fishermen shelter during storms. Twenty years later, that structure metamorphosed into a major military outpost. China’s gradual militarization of the Spratly Island features compelledPhilippine defense officials to “retain [their] presence” in the region. In 1999, Manila beached the Sierra Madre on Second Thomas Shoal.

Beaching the antiquated warship, however, was always a stopgap. Manila routinely dispatches resupply missions that carry food, water, fuel, and construction supplies to prevent the rotting ship from coming apart at the beams, which was once expected to occur as early as 2015.

Despite Philippine efforts to repair the derelict warship, China’s naval strategists have long anticipated the Sierra Madre’s demise. In 2013, People’s Liberation Army Gen. Zhang Zhaozhong explained: “Without the supply for one or two weeks, the troopers stationed there will leave the islands on their own. Once they have left, they will never be able to come back.” Zhang and likeminded Chinese military thinkers reckoned that enough menacing behavior would induce Manila to abandon the outpost permanently. Rather than directly harming the grounded ship — which remains commissioned in the Philippine Navy and thus part of Philippine sovereign territory — China began harassing and blocking resupply missions as early as 2013. Since 2021, the average number of Chinese ships near Second Thomas Shoal during resupply missions has quattuordecupled (yes, 14 times more). The Philippine ship count remains constant. Calculated maritime aggression has also become normalized in recent years as China tries thwarting resupply missions it suspects of ferrying construction and repair materials to extend the Sierra Madre’s longevity. Since 2023, Chinese units have blinded a Philippine Coast Guard crew with a military-grade laser. They have water-cannoned resupply vessels five times. And they have thrice collided with Philippine Coast Guard and resupply vessels.

Chinese belligerence, however, has backfired. In fact, it has galvanized Manila to bolster its defense of the shoal, with two major consequences for Beijing. First, if Beijing’s accusations ring true, Philippine forces may soon repair and reinforce the Sierra Madre enough to establish a permanent outpost. Second, China’s maritime maliciousness has emboldened Philippine President Ferdinand “Bongbong” Marcos, Jr., to reinvigorate his nation’s military alliance with Washington, resulting in agreements that grant greater U.S. military access to Philippine military bases and outposts. Philippine naval and air patrols with the United States, Australia, and Japan are also on the rise. The Philippines is once again a key American ally.

Presence and Bear Hugs

Many proposals to counter China’s revanchist aims at Second Thomas Shoal — and across the South China Sea — fall into one of two camps: presence or bear hug.

The first calls for a greater U.S. military “presence,” which entails sailing ships or flying aircraft near disputed territories to underscore a dispute’s legal or political significance. While initial presence patrols may check Beijing’s most aggressive maneuvers, a single American aircraft or warship would prove ineffective and be outgunned if the dispute turned violent, given the sheer preponderance of Chinese Coast Guard and Maritime Militia forces that stalk the Spratly Islands. What’s more, repeated presence patrols or pledges of support from the State Department do not fundamentally change Beijing’s strategic calculus. Washington could promise to defend the Philippines 30 more times, but that will not make China 30 more times likely to give up its quest to seize the shoal. Visible and vigorous manifestations of U.S. support, absent thus far, are the only way to compel China’s military to reconsider its aggressive aims.

In that vein, a growing number of analysts want the United States to hug the Philippines a lot tighter. Suggestions include increasing America’s military footprint near the shoal or helping the Philippines replace the Sierra Madre with a permanent structure. In these pages, Blake Herzinger proffered “Combined Forward Operating Base Sierra Madre.” Though noble and bold, proposals for direct American military involvement tempt conflict and paper over the stubborn capability gaps of the Philippine military. For example, Herzinger acknowledges that a U.S.-Philippine operating base could “elicit Chinese escalation” but downplays the severity of that sure-fire reaction. Chinese ships have rammed, lased, and blocked Philippine ships for carrying food and water. These ships would do far worse if Washington irrevocably endorsed Philippine sovereignty claims by building a permanent structure manned by U.S. Marines. In response, China could militarize Scarborough Shoal, obstruct Philippine hydrocarbon development and exploration, or drag the Sierra Madre off Second Thomas Shoal. Philippine leaders and voters remain wary of a permanent U.S. military presence on Philippine soil, too.

Who’s Been Seizing My Shoal?

Proposals to shore up the Philippine position at Second Thomas Shoal face a Goldilocks dilemma: Presence is too little, too late; bear hugs and American troops on Philippine soil risk provocation and overreach. Therein lies the rub: How can the United States support Philippine forces without triggering a clash with China?

The U.S. Navy and Coast Guard should provide the Philippines with the necessary resources and expertise to mount a credible defense against Chinese aggression. The United States must have skin in the game but avoid putting boots on the ground. It starts with four initiatives:

A Maritime Domain Awareness Center

Philippine units face significant challenges tracking and navigating around myriad Chinese Coast Guard cutters and Maritime Militia boats due to inadequate intelligence capabilities. In addition, Chinese forces often conceal their movements by disabling automatic identification systems, which makes monitoring Chinese activity more complicated and resource-intensive.

To address this, the United States and the Philippines should create a combined surveillance center in Palawan to monitor Chinese activities near Second Thomas Shoal, modeled after the Fijian-Australian Maritime Essential Services Center in Fiji. America and its capable partners could leverage reconnaissance satellites to tip and cue a full suite of unclassified, commercial imaging and sensing technologies, including space-based, airborne, maritime, and undersea unmanned systems, that provide comprehensive and consistent coverage of Second Thomas Shoal. American intelligence professionals could collaborate with their Philippine counterparts to integrate sensor data into a cohesive and releasable operational picture. The center can operationalize this intelligence by relaying and anticipating Chinese movements to Philippine command and control nodes (both afloat and ashore) via satellite communications, high-frequency radio, or datalink to maximize redundancy. Besides improving real-time Philippine awareness, this intelligence could also feed into long-range missile training drills at Philippine coastal defense sites.

Give the Philippines More Ships

For every Philippine naval or coast guard ship, there are about five Chinese naval and coast guard ships — not to mention the overwhelming displacement and weaponry of China’s cruisers, corvettes, and cutters. Nonetheless, the tyrannies of distance and priorities work in Manila’s favor. By increasing the number of Philippine naval and coast guard assets stationed at nearby Palawan, Manila can gain an early numerical advantage in a crisis over Chinese naval forces operating in the South China Sea, which primarily sortie out of faraway Hainan Island. Additional ships would also help resupply units exploit gaps within the great wall of Chinese ships that surrounds the shoal during routine resupply missions.

While recent acquisitions from Israel, Japan, and the U.S. Coast Guard have shored up the Philippine Navy’s fleet of patrol ships, a more diverse and capable set of ships is needed to rectify the Philippine Navy’s anemic order of battle. The U.S. Navy should consider transferring one decommissioned littoral combat ship, along with a training crew, to the Philippines. This “urban street fighter” packs naval strike missiles, an unmanned ribbed boat, a Fire Scout aerial drone, and a video camera, making it an ideal command and control platform capable of operating near the shoal while recording China’s most provocative behavior.

Diversifying the Philippine resupply fleet is equally important. Leasing the Marine Corps’ landing craft, air cushion or partner nations’ high-speed interceptor boats, such as the United Kingdom’s Pacific 24 rigid inflatable boat, would offer significant advantages in stealth and speed.

People to People

Naming and shaming China’s aggression during contentious resupply missions is a good start, but it is not enough to garner widespread international recognition of Philippine sovereignty over the shoal. The problem is not just that China water-cannons and rams Philippine units, but also that China outright rejects the 2016 United Nations Convention of the Law of the Sea tribunal ruling, which nullifies China’s claims to the South China Sea, including Second Thomas Shoal. The United States can spotlight the illegality of China’s maritime insurgency through a public relations campaign that unequivocally recognizes and advances Philippine maritime sovereignty.

As the Philippines gathers evidence to pursue legal action against China’s destructive maritime environmental practices within the Philippine exclusive economic zone, the U.S. Navy could deploy a Pathfinder-class survey ship to document environmental damage near Second Thomas Shoal via biological, physical, and geophysical surveys. Researchers with the National Oceanic and Atmospheric Administration and the U.S. Geological Survey could investigate near the shoal — or even temporarily embark the Sierra Madre — to inform strategies for protecting and restoring the local ecosystem. With enough American expertise and backing, the Philippines could take China back to international court, undermining China’s professed stewardship of the environment and international law. U.S.-Philippine scientific research missions near the shoal not only “civilianize” the Philippine claim to the shoal, but they also allow for an expansion of allied operations without triggering an escalation from China, as Chinese units are less likely to strike research vessels manned by scientists.

The U.S. Navy should also deploy sailors to Philippine Navy and Coast Guard vessels operating near the Spratly Islands. In return, the U.S. Navy could host Philippine personnel aboard Seventh Fleet or Third Fleet units. Such exchanges offer enhanced interoperability as both countries discuss and delineate tactical responsibilities during wartime and peacetime operations and try to grapple with the other’s tactics, techniques, and procedures. The presence of American sailors on Philippine ships near the contested shoal could again mitigate Chinese hostility, as China avoids actions that risk harming embarked U.S. personnel. Military exchanges would also be a public relations coup as American and Philippine forces literally stand shoulder-to-shoulder to safeguard a free and open Indo-Pacific and uphold Philippine sovereignty.

Prepare for the Worst

Deterring or repelling a Chinese takeover of the shoal demands a formidable allied defense that is primed for conflict. The United States should invite Australia, Japan, and the Philippines to form a crisis management task force to think through the very real threat of conflict at Second Thomas Shoal. The task force’s wartime preparations could start with three initiatives.

First, decide on clear redlines that, if crossed by Chinese forces, would trigger U.S. mutual defense commitments. These redlines should be privately relayed to Beijing. There should be no ambiguity regarding America’s support for the Philippines and the acts of aggression that would trigger a military response.

Second, capitalize on the recent string of successful U.S.-Philippine military exercises by hosting biannual multilateral drills that simulate contested resupplies or a conflict at Second Thomas Shoal. These exercises, held in waters outside the South China Sea, should address training shortfalls and include often overlooked scenarios. Serials should involve air-dropping supplies, resisting Chinese search and seizure attempts, small ship evasive maneuvering drills, medical evacuation training, combined reconnaissance air patrols, and floating defensive barrier training (including how to lay and how to avoid these obstacles).

Lastly, outline the feasibility, composition, deployment, rules of engagement, and logistical needs for an allied “rapid response” or “tripwire” force. Task force partners should determine how they will respond to a fight before it starts.

High Noon at the OK Sho-rral?

Discussions about Second Thomas Shoal invariably reference Article 4 of the 1951 Mutual Defense Treaty. It promises the United States will “act to meet the common dangers” posed by an armed attack on the Philippines, and vice versa. To prevent Article 4 from ever being invoked, however, American and Philippine security doyens should heed Article II: “[T]he parties separately and jointly by self-help and mutual aid will maintain and develop their individual and collective capacity to resist armed attack.”

China may hold escalation dominance over the Philippines, but its willingness to escalate will almost certainly wane when faced with a fortified, resilient Philippine defense, aided by tangible and unquestionable American support. Then, and only then, will Manila persuade Beijing that the South China Sea’s “juice” isn’t worth the “squeeze” at Second Thomas Shoal.



Nick Danby is an active-duty U.S. Navy intelligence officer. He recently concluded a two-year operational tour in the Western Pacific theater. He graduated magna cum laude with highest honors from Harvard University.

The views expressed in this article are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. government.

Image: ChatGPT