Despite considerable challenges, a naval blockade is both operationally and strategically possible, albeit only within certain limits.

The mounting challenge presented by China’s military modernization has led the United States to review existing military strategies and to conceptualize new ones, as illustrated by the ongoing debate over AirSea Battle (ASB), a new concept of operations put forward by the Department of Defense. But in the universe of possible strategies, the idea of a naval blockade deserves greater scrutiny. By prosecuting a naval blockade, the United States would leverage China’s intense dependence on foreign trade—particularly oil—to debilitate the Chinese state. A carefully organized blockade could thus serve as a powerful instrument of American military power that contributes to overcoming the pressing challenge of China’s formidable anti-access and area denial (A2/AD) system. A blockade could also be easily paired with alternate military strategies, including those based on ASB.

In the context of a Sino-American war, the United States could try to take China’s greatest national strength—its export-oriented, booming economic-growth model—and transform it into a major military weakness. To do so, the United States would implement a naval blockade of China that attempted to choke off most of China’s maritime trade. Under the right conditions, the United States might be able to secure victory by debilitating China’s economy severely enough to bring it to the negotiating table.

(This first appeared in October 2014.)

Yet until recently, a blockade strategy was largely overlooked, perhaps because economic warfare strategies seem inherently misguided given the close commercial ties between China and the United States. But if a serious conflict between the two nations erupted, then their immediate security interests would quickly override their trade interdependence and wreak enormous economic damage on both sides, regardless of whether a blockade were employed.

Even if a blockade is never executed, its viability would still impact American and Chinese policies for deterrence reasons. The United States’ regional strategy is predicated on the belief that a favorable military balance deters attempts to change the status quo by force, thus reassuring allies and upholding strategic stability. The viability of a blockade influences this calculus, and can accordingly affect American and Chinese actions—both military and nonmilitary—that are based on perceptions of it. If a naval blockade is a feasible strategy, it strengthens the American system of deterrence and dilutes any potential attempts by China to coerce the United States or its allies. Moreover, if a blockade’s viability can be clearly enunciated, it would also enhance crisis stability and dampen the prospects of escalation due to misunderstandings—on either side—about the regional balance of power. In short, as Elbridge Colby put it: “the old saw remains true, that the best way to avoid war is to prepare for it.”

While a blockade is not a priori impossible or irrelevant in any situation, it is also not a ready tool in the American arsenal and would be feasible mainly within certain boundaries. Most importantly, many commentators miss the fact that a blockade is a context-dependent strategy, one that crucially depends on the regional environment.

The Strategic Context

A blockade would not be employed lightly by the United States, given its significant potential costs. Accordingly, Washington would likely only consider employing a blockade in a protracted conflict over vital interests; anything less would simply fail a basic cost-benefit analysis.

More importantly, though, a blockade strategy would depend on the cooperation of several third parties in the region. After all, China’s trade is borne on the seas largely as a result of economic considerations rather than physical limitations; if China were blockaded, it would turn to the countries on its borders for help.

While many of its neighbors would be unable to make a strategic difference because of their rugged geography or their small size, three could prove vital: India, Japan, and Russia. The latter two would be important in helping the United States by cutting off China’s trade routes in its south and east, respectively, through implementing national embargoes on China and pressuring their smaller neighbors to do the same. Without their cooperation, the United States’ task would become much more difficult.

The last of the three neighbors—Russia—would be the lynchpin of a successful blockade, and could tip the balance of a blockade in favor of either China or the United States. On the one hand, Russia is remarkably well-positioned to alleviate the blockade’s effects on China. Russian trade would be immune to American interdiction, since Russia’s nuclear arsenal and significant conventional assets preclude any serious American attempts at military coercion. But on the other hand, China’s northern neighbor could also sound the death knell for China’s ability to resist a blockade. On the political level, Moscow continues to exert sway over the decisions made in the capitals of China’s Central Asian neighbors and could convince them to refuse Chinese entreaties to act as transit states. It could also guarantee that China’s two neighboring oil producers would no longer supply it with petroleum.

Accordingly, for the United States to implement a strategically effective blockade of China, it would strive to build a “minimum coalition” with India, Japan, and Russia. If all three states made common cause with the American blockade, then China would be placed in both an economic and a political stranglehold. If not, however, a blockade strategy would regionalize a Sino-American war in a way that would be fundamentally unfavorable to American interests.

Such a minimum coalition could only arise in one way: on the heels of an assertive Chinese push for regional hegemony that precipitates local support for a drastic American response. Short of anything but an aggressive China, collective embargo action will be deterred by the potential consequences of a blockade, not least of which is the possibility of a larger regional conflict with China. The four states are unlikely to coalesce together around an implicit containment policy until each feels that its national interests may be threatened by China in the future.

While such a possibility may appear distant at present, the United States, Japan, India and Russia all fear that Beijing might someday conclude that it must use force in order to protect its interests and to resolve its security dilemma on favorable terms. All four powers have increasingly hedged their bets against this possibility. If China’s power and influence in Asia continues to increase, then the bonds between all four states will strengthen, not out of any conviction about China’s belligerent intentions, but rather because of a profound uncertainty as to their future disposition.

The Central Operational Challenge

Even assuming that the United States can rally the necessary coalition together, it would squarely face an operational challenge that bedevils all modern-day blockade strategies.

Operationally, blockades are characterized by their distance from the coast of the blockaded state, and they come in two forms: close and distant. A close blockade is typically enforced by stationing a cordon of warships off an enemy’s shores to search all incoming or outgoing merchant ships and to impound those carrying contraband. Over the last century and a half, though, close blockades have become increasingly dangerous as belligerents developed the technology to project power from their coasts. In response, blockading powers have turned to distant blockades. A distant blockade avoids the military hazards of being located near the enemy’s shores by stationing itself at a distance, albeit still astride the enemy’s sea lanes, and it then chokes off the enemy’s trade in a similar manner to the close blockade.

Neither a close nor a distant blockade of China alone would be successful thanks to the constraints imposed by military requirements and the nature of maritime commerce. On the one hand, a conventional close blockade would be severely complicated by the United States’ desire to minimize the military risk to American warships. As American forces came closer to China, they would increasingly place themselves within range of China’s A2/AD complex, possibly limiting their operational freedom and resulting in heavy losses. American forces could avoid the perils of China’s A2/AD system by implementing a close blockade enforced by submarines, long-range air power, and mines; but by so doing, the blockade would also lose much of its ability to differentiate between neutral and enemy commerce.

On the other hand, the logic behind conventional distant blockades has similarly been undermined by the exigencies of modern commerce. Today’s cargoes of raw materials and merchandise can be sold and re-sold many times in the course of a voyage, so the ultimate ownership and destination of a ship’s cargo is often unknowable until the moment it docks. Although the United States might be able to set up a conventional distant blockade that quarantined all Chinese-owned or -flagged vessels, China could still simply buy neutral vessels’ cargoes after they had passed through the blockade, defeating its entire purpose.

The Solution: A Two-Ring Blockade

To remedy the infirmities of the two blockades, the United States would take the best of both worlds and implement a “two-ring” blockade made up of two concentric rings around China’s shores.