Delay, Disrupt, Degrade: Mine Warfare in Taiwan’s Porcupine Defense
In October 1884, as part of the wider Sino-French War, a contingent of heavily armed French warships sailed toward the harbor of Tamsui, in northern Taiwan. When the fleet approached the estuary of the Tamsui River, nine naval mines and boats loaded with stones blocked its path. Prevented from sailing into Taipei, French commanders dispatched their marines, but they fared little better. After several hours of fighting on land they were driven back into the sea.
Today, Taiwan again faces the threat of invasion — this time from China. As Taiwan’s leaders consider their defensive options, the Battle of Tamsui may also hold answers.
U.S. officials and Taiwanese strategists have argued that Taiwan’s best defense is to become a “porcupine,” bristling with “a large number of small things.” Military analysts have proposed denying air superiority to China via mobile surface-to-air missiles and drones and creating a “prickly fortress of sea denial” with road-mobile anti-ship missiles. What is largely missing is a similarly detailed discussion of the concepts and tactics for mine warfare. The naval mine, however, as RAND’s Scott Savitz has argued, is one of the most potent and cost-effective denial weapons available to Taiwan.
Strategically placed naval mines would allow Taiwan to leverage its natural geographic advantages to strengthen deterrence by denial and build a formidable defense in depth. Exploiting Taiwan’s shallow waters and treacherous coastline, mines employed at different water depths and locations would offer Taiwan a low-cost and effective means to delay, disrupt, and degrade Chinese forces. Taiwan could integrate these concepts, slowing down a Chinese invasion and interfering with its timing and tempo by channeling Chinese movements into corridors for Taiwan’s anti-ship missiles, gun batteries, and drones, inflicting significant attrition.
Sea mines are, of course, not a panacea to solve all the security threats facing Taiwan, which include gray-zone activities and a blockade of the island. Protective mining would likely be less useful to defend Taiwan against these other forms of Chinese coercion, but to the extent that China might employ such means to weaken Taiwan in advance of an amphibious invasion, mining would still offer Taiwan a valuable line of defense. To exploit mine warfare in this way, however, Taiwan would need to make it an investment priority, expanding the size and diversity of its mine stockpile and minelaying capabilities and improving its readiness to execute such a campaign.
Taiwan’s Deterrence Challenge
The credibility of Taiwan’s deterrence depends on convincing China it cannot accomplish a fait accompli, rapidly seizing the island before coalition forces have time to intervene. Given that Taiwan cannot match China ship for ship, or missile for missile, strategists have called on Taipei to adopt an “asymmetric” approach. Lee Hsi-min, a retired admiral and former chief of staff of Taiwan’s armed forces, for example, has developed an overall defense concept, which envisions employing numerous small and low-cost systems in a distributed way that can survive an initial bombardment and then conduct a protracted and effective resistance.
Taiwan has two critical advantages — it only needs to contest sea control to deny China a victory, and it would be fighting from its home territory. The British naval theorist Julian Corbett distinguished between sea control, aimed at securing freedom of action and maneuver at a specific time and place, and sea denial, which seeks to prevent an adversary from gaining such control. Taiwan only needs to achieve sea denial, which is much easier than the sea control required for a successful amphibious attack. Given that the People’s Liberation Army would need sea control to support amphibious operations, Taiwan’s strategy should aim to convince Beijing it cannot obtain it. Employed in a way consistent with international law, naval mines placed on Taiwan’s western coast and within its own waters can contribute directly to sea denial, restricting the invasion fleet’s access to the littorals and limiting its freedom of movement.
Taiwan’s geography is especially favorable to a sea denial campaign and to the use of mines. The waters off the island’s west coast, including those to the north and south of its largest ports, are shallow, making them ideally suited for mining. With a limited number of beaches suitable for an amphibious landing and many of these quite narrow and steep, Taiwan would be able to concentrate its mining efforts in a discrete number of locations. The shallow depths and mudflats surrounding Taiwan would enhance the effects of naval mines laid near its shores, making it easier to channel Chinese forces into areas where they are most vulnerable to Taiwan’s other defenses.
Three Concepts of Sea Denial
Protective mining operations would allow Taiwan to deny a Chinese fait accompli through three primary mechanisms: delaying the amphibious assault, disrupting the attacker’s plans, and degrading the advancing forces.
Operations to Delay: For Taiwan, delaying the arrival of the People’s Liberation Army on its shores with the use of naval mines would give its forces additional time to organize a defense and require China to divert significant resources to costly and personnel-intensive minesweeping operations.
Taiwanese mines — or suspected mines — would provide one of the “outer layers” of a defense in depth, requiring the People’s Liberation Army to fight its way past each layer. By combining different types of mines, employed at different water depths and varied distances from shore, Taiwan could create a multifaceted and hard-to-solve problem for China. The People’s Liberation Army Navy would have to deploy assets to neutralize the mines or find alternate routes, both time-consuming processes. With many types of mines, China’s minesweepers would need to employ different types of countermeasures, multiplying the time required to clear or neutralize the threat. For example, Taiwan could employ bottom mines and a series of moored influence and moored contact mines to create a vertical “curtain” — varying both threat types and depths of placement to make it especially difficult for China to sweep the area.
Minefield density could also be leveraged as a tool to protract timelines. China has about 60 mine countermeasures ships, but not all vessels are able to clear all types of mines. Estimating based on historical averages and assuming that a third are not operationally ready due to maintenance, each of China’s 40 available minesweepers might clear 0.8 to 2 mines per day, for a total of 32 to 80 mines. Creating a Q-route, or cleared passageway, typically requires removing 10 percent of a minefield. Doing so through even a small minefield of 600 mines, therefore, could delay Chinese forces at least 0.75 to 1.8 days, and possibly longer if mines are laid close together. Large numbers of decoy mines, intermixed with real ones, could also be a cheap way for Taiwan to increase the time and effort required for Chinese mine clearance operations. Taiwan could cause further delays by targeting the minesweepers, which work in predictable patterns, with anti-ship missiles and loitering munitions.
North Korea’s mining of Wonsan Harbor in 1950 offers a model. After landing at Inchon on Sept. 15, Gen. Douglas MacArthur, the commander-in-chief of U.N. forces, ordered an amphibious assault on Wonsan to encircle enemy forces retreating from the south. With “mines too numerous to count” blocking the assault path to the beach, the U.S. Navy began a complex sweeping operation, resulting in the loss of four ships and a delayed start to the amphibious attack. “Those damn mines cost us eight days’ delay in getting troops ashore,” Adm. Forrest Sherman concluded, warning, “I can all too-easy think of circumstances when eight days’ delay offshore could mean losing a war.”
Operations to Disrupt: Mine warfare also offers Taiwan a low-cost way to interfere with China’s military plans, increasing the risk of operational failure. Any military operation — and especially one as complex as an amphibious invasion — is meticulously planned and choreographed ahead of time, but the People’s Liberation Army’s preference for highly scripted operations leaves it particularly vulnerable to disruptions and inhibits the battlefield adaptationneeded for success.
First, protective mining would deny China one of the attacker’s main operational advantages — the element of surprise. Chinese mine-clearing efforts would be easily detected. China likely lacks sufficient minesweeping capabilities to conduct multiple feints, making the location of Chinese clearing efforts one of the most reliable indicators of Chinese operational intentions. This early warning would allow Taiwan’s defenders to reinforce the one or two beaches where Chinese forces are sweeping the waters for mines.
Second, mines will impede the movement of advancing forces and upset even the best-laid plans. Mines provide a concealed threat, lurking below the surface, ready to strike. A ship damaged by an uncleared mine creates a collision risk for advancing ships, forcing the formation to redirect its route — a challenge exacerbated by the narrowness of Taiwan’s beaches and the approaches to them — and diverting other assets to support rescue efforts. Remote mines that can be activated at a time of Taiwan’s choosing could be especially effective for disruption operations, targeting vessels at key places within the invasion fleet’s formation. As other ships work to clear the obstruction and address the threat, the attention of the fleet is distracted from its primary mission. It can also trigger a cascading effect, leaving ships out of sync with the pre-planned movements of the amphibious assault.
The threat of sea mines can even be enough to halt an entire operation — the ultimate disruption. During the Great Retreat of the Russian army in World War I, Russian sea mines, supported by artillery and a naval squadron, were sufficiently dangerous to cause the Germans to end a naval operation threatening the Russian army’s seaward flank. “Operation against Gulf of Riga broken off in view of the presence of very powerful minefields, one following another,” the German commander reported. His minesweepers later managed to clear a passage through the mines and enter the gulf, but after spotting a floating mine he ordered the fleet to retire for the night. When the German ships returned the next day, they discovered the Russians had used that time to seed new minefields. The Germans called off the attack and withdrew.
Operations to Degrade: Finally, naval mines can degrade China’s capabilities to invade Taiwan, damaging or sinking Chinese ships, inflicting significant physical and psychological attrition to its invasion forces, and helping to offset an unfavorable balance of forces.
Mines can contribute to the degradation of Chinese forces in two main ways. First, they can inflict direct damage on Chinese vessels and landing forces approaching Taiwan’s beaches. Since World War II, for example, 15 U.S. Navy ships have been sunk or damaged by mines, amounting to about four times the losses of all other threats combined. Second, mines can indirectly contribute to damage by leading adversary forces into shallow and rocky waters and shaping the littoral environment. Taiwanese minefields arranged in strategic locations or patterns — for example staggered in tiers or overlapping bunches — could create barriers that, together with Taiwan’s inhospitable geography, channel the People’s Liberation Army into kill zones, allowing Taiwan’s anti-ship missiles, torpedoes, gun batteries, and drones to multiply their destructive effects and attrit China’s invasion forces.
The French and British learned this lesson during World War I when they attacked the Dardanelles in 1915, aiming to open the straits and seize Constantinople. The campaign was a disaster from the start. With the waters heavily mined, Allied ships were forced into narrow areas covered by the enemy’s coastal forts and heavy gun batteries. Commanders then attempted to take Constantinople by amphibious assault. Here too, mines were the Allies’ undoing. Enemy minefields channelized the Allied landing, restricting the size of the landing areas and limiting fire support and resupply. The result was a costly and failed campaign.
Building a Protective Mining Capability
Though mines would significantly strengthen Taiwan’s deterrence and defense, Taipei has not made the necessary preparations. Taiwan’s navy continues to prioritize small numbers of large surface combatants over acquiring the “large number of small things,” including sea mines, needed to implement an asymmetric strategy. Investing in the necessary capabilities and improving readiness to carry out mining operations, however, should be top priorities for Taiwan.
Materiel Gaps: Taiwan would need to address materiel gaps, both in mines and minelayers. Taiwan’s current stock of mines is relatively small and old. For a robust mine campaign, however, Taiwan would need large and diverse stocks of sea mines for creating layered minefields of many sizes and densities. Taiwan’s top priority should be acquiring numerous cheap and easy-to-produce mines, such as simple air- or surface-delivered moored contact mines or even homemade “MacGyver mines” made from waterproof landmines. Simple mines such as these can cost as little as $2,000 each but still cause much damage, especially if placed in water depths of less than 30 feet close to a landing beach, where they would cause casualties and subsequent delays.
In addition, Taiwan could acquire smaller numbers of more advanced influence and remote-controlled mines. Influence mines activate when they sense a ship’s acoustic or magnetic signature above them or are activated by the pressure created as a ship moves past and would be especially useful in the shallow waters of the Taiwan Strait. They can also be set with “ship counters” to activate when the second or n-th ship passes — letting minesweepers pass before targeting higher-value vessels. Remote mines would allow Taiwan to mine ports and beaches well in advance of any invasion attempt.
To lay these mines quickly, Taiwan would need to expand its minelaying capabilities. Taiwan could use aircraft or surface vessels to deliver the bulk of these mines. Civilian militia trained to push homemade mines off the back of small boats could also contribute. Taiwan has four new indigenously produced minelayers, but some advanced mines would require sub-surface delivery. Given Taiwan’s submarine fleet is small, it could acquire uncrewed subsurface vessels designed for minelaying, such as the U.S.-developed Orca system or explore cheaper options — similar to the underwater drones used in the Red Sea.
Readiness Gaps: A successful mine warfare campaign would also require training and staging to ensure Taiwan can quickly and effectively lay a large and diverse array of mines. Taiwan has conducted some small-scale minelaying drills, but most of its training on mines seems to focus on countermeasures. Taiwan should make minelaying a much more intensive part of its military training programs and a visible one — signaling to China that it has this capability.
A more robust training regime should focus on preparing Taiwan to quickly lay mines at scale. Relying mainly on inert mines (or even similarly sized balls or barrels) for these trainings, Taiwan could practice seeding ports and beaches. Taiwan should prioritize training its air, naval, and coast guard forces, but should eventually expand training to a civilian militia, working to integrate the island’s fishing fleet into minelaying operations.
More generally, Taiwan will need to develop operational plans that address questions of staging, timing, sequencing, and logistics of a protective mining campaign ahead of time. Given China’s missile threat to Taiwan’s surface or airborne minelayers, Taipei would want to have its minefields in place before the shooting war begins, creating several challenges for the island’s political and military leaders. For instance, Taiwan will need to decide at what point in a crisis — should a Chinese invasion appear impending — it would begin protective mining, including which ports and beaches to prioritize and how to distribute its stocks across locations. The stakes would be high, as protective mining could trigger public or economic panic and even offer Beijing a convenient casus belli to confuse international public opinion over who started the conflict, given both claim those territorial waters as their own.
To lay thousands of mines, Taiwan will need at least several days, if not more than a week, while taking care not to impede commercial traffic through the Taiwan Strait — a move that could prompt international backlash and cost Taiwan some of its international sympathy. To be ready, Taiwan should adopt procedures to allow for a rapid mining campaign, including distributing its mine stockpiles to numerous locations with easy access for use. It should also invest more in sub-surface delivered mines, especially remote mines that can be activated in the future, and simple mines that can be laid quickly in bulk. Finally, Taipei might consider socializing its plan for mining with international partners to consolidate their support.
Conclusion
On the shore of the Tamsui River today, a sculpture with a “dove of love and peace” sits perched atop yellow naval mines, commemorating the historic location where sea mines halted France’s invasion fleet from sailing into Taipei. The lessons the French learned at this site 140 years ago are no less true today: The naval mine remains an effective sea denial weapon to wield against an amphibious invader.
Jonathan Dorsey is a naval aviator, recently commanded a forward-deployed naval forces squadron, and is now a U.S. Navy fellow at the Stimson Center. The views expressed are those of the author and do not reflect the official policy or position of the U.S. Navy, Department of Defense, or the U.S. government.
Kelly A. Grieco is a senior fellow in the Reimagining U.S. Grand Strategy Program at the Stimson Center, a nonresident fellow with the Marine Corps University’s Brute Krulak Center for Innovation and Future Warfare, and an adjunct professor at Georgetown University.
Jennifer Kavanagh is a senior fellow in the American Statecraft Program at the Carnegie Endowment for International Peace.
Image: U.S. Navy Photo by Mass Communication Specialist 2nd Class Nick Bauer
