Since 1979, it has been the policy of the United States, as codified in the Taiwan Relations Act, to maintain the capacity to resist the use of force or other forms of coercion by China against Taiwan. Until recently it could be taken for granted that the United States was able to directly thwart a Chinese attack on Taiwan. But dramatic increases in China’s military capability over recent decades have called that into question, particularly with the military balance trending ever further in China’s direction for at least the near future.

With General Secretary Xi Jinping having reportedly directed his military to be ready to invade Taiwan by 2027, the United States and its allies are working on options to deter China, with a focus on denying the success of Chinese military aggression. However, given limited resources and self-imposed congressional budgetary limits, there is likely to be a strong temptation to look for less expensive solutions to deter such action. One line of thinking among some observers has been to deter China by threatening its sea lines of communication. According to this approach, in the event of a conflict, the United States could, for example, just “cut off their oil,” starving the Chinese military and economy.

Unfortunately, this is magical thinking. China’s leaders identified their “Malacca dilemma” more than 20 years ago and have been taking action since to become a maritime great power and mitigate such a risk. If Washington seeks comfort in easy but unrealistic solutions, it risks undercutting support for resources that will be necessary to actually deter China militarily.

The Temptation of Trade Denial

One such theoretical “low-cost option” is a “trade denial” strategy that appeared in a recent article in the U.S. Naval Institute’s Proceedings. The article’s author, Rear Admiral Monty Khanna, Indian Navy (ret.), does not advocate a blockade per se, considering it infeasible due to the internationalized nature of modern shipping, the risk of environmental disaster due to ship sinkings, and the likelihood that China could survive several months of attempted economic strangulation. On these points, Admiral Khanna is likely correct: consider the case of the Ever Given, the container ship that ran aground in the Suez Canal — Japanese-built and -owned, Panamanian-flagged, officered by Indians, and chartered by a Taiwanese company to take goods from China to Europe. Is such a ship “Chinese shipping,” to be sunk or boarded on the high seas?

Rather than strangulation, the goal of such an option would be to inflict an economic shock on China via the seizure of Chinese-flagged vessels in U.S. and allied ports. While such a cost imposition measure might be sensible to take in the event of a major U.S.-Chinese conflict, there are good reasons to doubt its effectiveness as a deterrence measure, making this a risky option on which to depend. In the absence of sufficiently robust military capabilities to actually defeat Chinese military aggression against Taiwan, its failure to deter could result in both an otherwise preventable war and a military defeat for the United States and Taiwan, in addition to the escalation risks that can accompany cost imposition measures.

A Problem of Scale

To properly assess such a strategy, one must first appreciate the sheer scale of China’s maritime sector. In 2023, China passed Greece to become the world’s largest shipowner, with over 249 million gross tons of shipping, and it owns more than 11,000 merchant ships with Hong Kong included. In terms of actual Chinese- and Hong Kong–flagged ships, China is in third place, but is only surpassed by flags of convenience Liberia and Panama — states with little to no geostrategic heft.

One might think ownership versus a ship’s flag state to be a distinction without a difference. But Admiral Khanna himself points out there is one, as additional measures would be needed to ensnare more ships on the basis of ownership as opposed to their flags. One would also be wise to consider how difficult ownership might be to establish in some cases, as China is well practiced in using shell companies and similar measures to avoid sanctions during conflict.

To properly consider seizures of Chinese-flagged vessels, you have to understand where they are likely to be operating: looking at automatic identification system data for such ships, it quickly becomes apparent that the vast majority of them stay fairly close to China. While there is a sprinkling of Chinese-flagged ships around the world, most Chinese ships are engaged in coastal trade within the First Island Chain, and as such are unlikely to be in a position to be seized at the start of a conflict. Hong Kong–flagged ships are a bit more evenly distributed around the globe, but there may be enough fuzziness regarding Hong Kong’s national status to convince nervous allies not to seize them. In any case, many could be transferred to flags of convenience in anticipation of a conflict, for which China will presumably set the timing. That factor — that China, as the aggressor, will likely determine the timing of a conflict — could matter a great deal. Put simply, if a plan to deter China relies in a significant way upon seizing its ships at the outset of a conflict, China could mitigate the plan’s effectiveness by simply minimizing the number of ships in harm’s way at such a time.

There is also, again, the problem of scale — and the resources available to implement a trade denial strategy. Admiral Khanna states, correctly, that any ship could be monitored by the U.S. Navy, which could choose to interdict it in a manner of its choice. But while on any given day, any ship could be dealt with, that is far from saying that most Chinese ships could be at any given time. There are more than 12,000 Chinese- and Hong Kong–flagged seagoing merchant ships, while the U.S. Navy has fewer than 300 warships of all kinds, with little growth in those numbers imminent. What’s more, of the limited number of U.S. Navy warships, many will be engaged in trying to save Taiwan, or dealing with fires likely to break out elsewhere around the world. And too many are also likely to be in maintenance. With probably at best one-quarter in long-term maintenance, and perhaps half engaged in combat in the Pacific, that would leave roughly one-quarter of the fleet to deal with everything else. Were all of those remaining warships assigned to trade denial, there would be more than 150 Chinese merchants for each one.

It is in part due to this sort of math that Fiona Cunningham concluded in a detailed article that the United States “would not be able to use a distant blockade to manage escalation risks in a conflict over Taiwan … if it deployed forces … as part of the primary campaign and those forces needed to be protected by suppressing Chinese area-denial capabilities.” Also, while Admiral Khanna advocates requisitioning or chartering vessels to supplement U.S. and allied naval assets, there is good reason to doubt that such an effort could be set up at the scale and speed required to prevent a Chinese fait accompli over Taiwan. And in any case, the United States will be challenged to get enough vessels to supply its own logistical needs before adding any further missions.

If one were instead to count on an actual blockade to strangle China, as opposed to Admiral Khanna’s trade denial option, there would be other challenges. First, such a blockade is likely to be militarily contested by China: a review of Chinese open-source literature indicates that one of the primary missions for China’s small but growing number of overseas bases would be to support securing its sea lines of communication in the event of a conflict. On top of that, most ships going to and from China are most likely not Chinese-flagged or -owned. As such, with the internationalization of most shipping (see Ever Given), and many options to reroute goods and oil cargoes after passing through a U.S. and allied distant blockade, the only sure way to block China’s trade is to actually prevent access to its ports. With manifold threats from China’s legion anti-ship and anti-air capabilities covering the approaches to those ports, that would likely mean a campaign focused on a limited number of U.S. and allied submarines and long-range antiship missiles — platforms and munitions that would be needed for doing things like attempting to stop an invasion of Taiwan.

Conclusion

In the end, while methods like those discussed above certainly constitute measures that should be considered in the event of a conflict with China, U.S. and allied defense thinkers should not assume that they provide an assured, low-cost alternative to deter Chinese military aggression. Neither these nor other so-far-theoretical capabilities provide a dependable alternative to the hard, costly measures that are urgently needed and not being sufficiently resourced thus far. U.S. defense spending is much lower as a percentage of gross domestic product than it was during the last Cold War, and China’s is likely far larger than its official numbers. Given China’s apparent plans for attacking by surprise, disrupting command and control networks, and imposing an air and naval blockade prior to an assault, the only assured way to deter an attack on Taiwan is to have sufficient survivable forces and munitions properly postured before a Chinese attack. These forces should be ready to employ proven concepts of operation, have clear rules of engagement (including against erstwhile civilian platforms), not be dependent on anything more than episodic communication, and not depend on vulnerable fixed facilities within range of China’s precision strike forces. Relying on anything else constitutes wishful thinking and a false sense of economy, potentially resulting in far more costly and devastating consequences in the event of a failure of deterrence.

Retired Capt. Thomas Shugart, U.S. Navy, is a former submarine warfare officer, an adjunct senior fellow at the Center for a New American Security, and the founder of Archer Strategic Consulting.

Image: Petty Officer 3rd Class Andrew Langholf