Iran’s shuttering of the Strait of Hormuz, and the United States’ failure to restore the free flow of maritime traffic, has put a spotlight on just how much the global economy depends on ships’ ability to pass unencumbered through key waterways—and how fragile that right is. But well before the strait’s closure, a long era of free seas was already coming to an end.
Critical maritime chokepoints around the world have become fraught with new risks. Beginning in late 2023, for instance, the Iranian-backed Houthi militia in Yemen has throttled transit through the Red Sea, forcing major shippers to reroute away from the Suez Canal and Bab el Mandeb Strait. Since at least 2022, China has mounted increasingly aggressive exercises and activities in and around the Taiwan Strait, triggering great anxiety about the vulnerability of semiconductor supply chains. Russia’s hybrid warfare in the Baltic Sea, Ukraine’s unexpected success attacking Russian vessels in the Black Sea, and even the United States’ lethal campaign against alleged drug-smuggling boats and its hot pursuit of shadow fleet tankers have all badly shaken the impression that the oceans are relatively free to navigate.
These accelerating challenges to free navigation are fragmenting the formerly open trading system. Throughout the eight decades after World War II, those engaging in commercial maritime trade—which constitutes roughly 80 percent of global trade overall—could largely afford to ignore these kinds of threats. A framework of multilateral treaties and legal norms established order in the littoral zones (coastal areas and narrow straits that channel trade) that had previously been governed by whoever could effectively control them. With unmatched military power throughout much of this period, the United States policed this relatively free zone of commerce. Now, a proliferation of challenges to free navigation is threatening the world’s open trading system. Washington still commands the strategic heights and depths, fielding the world’s most capable force of aircraft, warships, and submarines, as well as dominating space communications. But changes to trading patterns, military technology, and the economics of warfare are eroding the efficacy of U.S. military power in contested littoral zones.
Like Wile E. Coyote running off the cliff and staying aloft until he looks down, Washington has belatedly discovered that its military power cannot provide sufficient lift for its soaring global ambitions. Without the ability to control crucial waterways, straits, and other littoral zones, the United States can no longer reliably secure the economic system that has underwritten an unprecedented era of openness and prosperity. Today, both small actors and the United States’ greatest competitor, China, no longer need to challenge U.S. conventional military supremacy in these domains directly. They can do so obliquely and asymmetrically, using cheap but long-range drones and missiles or economic tools that prevent open access without firing a shot.
Even if the United States were to sink extraordinary resources into an attempt to reestablish a high degree of control over the commons, restoring the old maritime order is no longer a realistic aim. Sea changes in military technology and industrial production are undermining the basic feasibility of a truly open order. Reckoning with this structural shift is a generational challenge that must begin with making peace with the fact that the American way of war is mismatched with the contemporary world’s strategic and economic geography.
FREE REIGN
The maritime order has long been defined by a tension between states’ wish to navigate the seas freely and their temptation to control maritime space. Between the early eighteenth century and the middle of the twentieth century, these antithetical desires were reconciled by the so-called cannon-shot rule, a custom according to which a state’s authority over the sea extended only as far as its cannons could reach, a range considered to be about three nautical miles. This customary rule, recognized only by the colonial powers, permitted the strongest naval and commercial fleets to dominate the maritime commons and build global empires while assuring other states at least some measure of control over their coastal approaches. In practice, the rule afforded great advantages to a select few maritime powers, especially the British Empire. Their advanced vessels and distant naval outposts produced the first truly global trading routes and subordinated other states unable to project power beyond a narrow coastal band.
This compromise began to unwind in the early twentieth century, with the advent of modern submarine and mine warfare and the advancement of weapons technology that extended strike range from air, land, and sea. After World War II, the traditional cannon-shot rule was gradually buried under an elaborate multilateral architecture, beginning with the Geneva Conventions in 1958 and culminating in the Third United Nations Convention on the Law of the Sea (UNCLOS III) in 1982. On paper, at least, these formal rules assigned all coastal states certain geographically defined entitlements—zones of jurisdiction determined by treaty, not by naval tonnage or coastal artillery. All states enjoyed freedom of navigation, overflight, and laying of submarine cables anywhere outside a somewhat expanded, fully sovereign territorial sea of 12 nautical miles.
American might underpinned a maritime order from which most nations benefited.
Washington became this framework’s guardian—an offshore balancer operating at a comfortable geographic remove, with its power projected from highly maneuverable carriers, lurking submarines, blue-water cruisers and destroyers, and stealthy aircraft. With formal treaty rules underpinned by the U.S. military’s formidable power and ubiquitous presence, any trading vessel plying the world’s oceans enjoyed an unprecedented level of security in peacetime. This era of multilateral treaty law institutionalized a general pattern of open access to resources and markets anywhere, ushering in an era of unfettered globalization.
Although other nations fielded missile, air, and naval capabilities that could range well beyond their coastal zones, American might underpinned a system in which most nations benefited and few launched overt challenges. At times, of course, Washington also viewed itself as too powerful to be constrained by international law, stubbornly refusing, for instance, to formally accede to UNCLOS III because of relatively minor concerns about the deep seabed mining regime. Yet the United States’ commitment to free navigation remained a grounding norm, a reliable check on power projection capabilities creeping out to sea.
By the turn of the twenty-first century, the United States had achieved what the political scientist Barry Posen, in 2003, called “command of the commons”: an unrivaled ability to use the world’s oceans, air, and space for military purposes, paired with the capacity to deny adversaries comparable use during conflict. Posen was also careful to demarcate the limits of this command. The United States, he argued, was not invulnerable in airspace below 15,000 feet or on the ocean within a few hundred miles of a reasonably well-defended coast. Two decades before the cracks in America’s command of the commons became fully visible, he accurately named the powers most likely to test its limits: China and Iran. Although U.S. submarines ruled the undersea battle space and its air force reigned in high altitudes, this uncontested control necessarily thinned out closer to hostile territory.
LONG SHOTS
Still, the Pentagon’s defense strategies routinely invoked Posen’s concept and extended it to cover areas he had expressly excluded, including cyberspace. Washington came to believe both that it exerted nearly untrammeled control over the highest altitudes, the deepest fathoms, and the most dangerous shorelines and that it ought to retain that control—to be able to maneuver nearly everywhere, all the time, at a moment’s notice. But the United States’ command of the commons, and particularly the littoral waters, was always more circumscribed than imagined in the Pentagon’s strategic documents. These assumptions are now facing their harshest test yet in the Strait of Hormuz, and the broader military, legal, and economic frameworks that underpinned freedom of navigation are straining under the weight of new and mounting pressures.
Long-range precision missiles and inexpensive drones fired from mobile artillery can now strike virtually anything that floats thousands of miles from shore and challenge everything that flies below 100,000 feet above the earth’s surface. These advances in offensive technology are producing a reversion to the historical mean. The cannon-shot rule is reasserting itself, because the range of a “cannon” has been extended dramatically and adversaries have begun to test the assumption that the U.S. military is untouchable and omnipresent. It is growing far easier for a far wider array of actors to delay or deny access to the chokepoints through which the world’s commerce once flowed freely.
Ultimately, however, changes in military technology are only partially responsible for collapsing freedom of navigation. Offense-defense balances inevitably shift. But the shift in the economics of defense and trade is the more profound and enduring challenge. The Houthis in Yemen can buy an attack drone for a few thousand dollars; to intercept it, the United States uses an interceptor that costs roughly $2 million. It takes a $3 million Patriot round to counter a Shahed missile Iran can acquire for around $35,000. In nearly three years of effort to fully thwart the Houthis’ campaign to disrupt Red Sea shipping, the U.S. Navy has expended some $2 billion in munitions to protect its own ships—before accounting for the expense to crew and maintain these vessels and aircraft, the opportunity costs of not deploying them (or not deploying them elsewhere), and the inestimable reputational harm of fighting a ragtag militia to a draw. To avoid risk, major shipping carriers—and U.S. naval forces—have continued to take the long way around the Cape of Good Hope.
Currently, any defense of free navigation in contested littorals is bounded by a defense industrial base that takes years to replenish magazines. In America, a master chef is making slow and exquisite dinners, but its adversaries are now short-order cooks, dishing out a ready supply of meals thrown together with commercial components provided by China’s massive industrial surpluses. China’s strategic calculus in such conditions is a no-brainer: each scarce U.S. interceptor expended to counter a small adversary’s drone is an interceptor that the United States cannot use against far more capable and numerous threats in the Pacific.
TRAGEDY OF THE COMMONS
In practice, Washington’s idea that it needed to command every sea all the time put unmanageable burdens on the Pentagon, which became saddled with a strategy, industrial base, and economic model that was no longer fit for purpose. By 2013, when the U.S. Navy began forward deploying the Littoral Combat Ship (the vessel it designed for contested coastal waters), the ship failed to prove that its modular design and light armament worked for the operations it was intended for. That abortive experiment yielded to the Constellation-class frigate, another small surface combatant that was scrapped before any ships of its class even hit the water. Both programs were hampered by avoidable dysfunction in the U.S. acquisition process and industrial base, but they also fell short because the affordable crewed warship had been squeezed out of existence. It was too vulnerable to survive the high-end fight that great-power competition requires and too costly to serve as expendable mass against cheap, precise weapons. In shipyards and straits alike, a new cannon-shot rule has been eroding U.S. command at sea, leaving no profitable middle ground.
China, meanwhile, was pursuing a military modernization program that was not designed to challenge the United States’ outright control of global waterways but, rather, to deny local maritime, air, subsea, and information space to its sole rival. The Pentagon’s annual report on Chinese military power illustrates this area denial system as a set of range rings, concentric arcs radiating from China’s mainland coast, each marking the reach of a certain type of missile. Chinese short- and intermediate-range systems now saturate its near seas, and a suite of submarine and bomber-launched cruise missiles can strike U.S. bases in the central Pacific. These systems are far more sophisticated than Houthi drones. But the strategy behind them operates on the same principle: quantity will defeat quality. This strategy is rooted, ultimately, in an economic logic.
The scale of China’s industrial base enables a coercive reach that likely defeats the free access and maneuver on which U.S. strategic plans depend. One offset to this scale disadvantage is that the United States still has a clear and perhaps enduring advantage in its submarine fleet. China is struggling to build comparable nuclear boats. Russia fields near-peer capabilities (which, so far, it has resisted transferring to China), but it faces stark capacity constraints, especially since it invaded Ukraine in 2022. Yet even this advantage is diminishing as new fixed and mobile undersea sensing—much of it concentrated in the western Pacific—makes it steadily harder for submarines to hide. Ukraine’s drones have decimated the Russian Black Sea Fleet—a truly remarkable feat for a nation lacking a navy, and perhaps the strongest example of the radically disruptive nature of the new cannon-shot rule.
The undersea contest goes even deeper—down to the seabed, where power, energy, and fiber-optic data cables can be cheaply severed and only repaired at great cost in time and resources. Simple fishing boats and barges can sever cables with dragging anchors and have done so repeatedly in the Baltic Sea and the Taiwan Strait. A variety of new acoustic sensors—including those integrated into data cables—and others finding magnetic, hydrodynamic, and seismic signatures are making it harder for submarines to hide. China, in particular, has invested heavily in fixed and mobile undersea sensing. This network may lack the geographic scope and proven utility of the American systems, but it is heavily concentrated in the western Pacific—which Beijing regards as the sole theater of potential great-power conflict—as an “undersea great wall.”
With the exception of China’s direct challenge in the western Pacific, the United States’ maritime power is not being usurped by a rival fleet but by asymmetric tactics well beneath the depth ratings of the U.S. Navy’s submarines. Meanwhile, overhead, cheap and readily available commercial imagery and communications enabled by Russian and Chinese satellites now furnish a superpower’s battlefield awareness and targeting precision to adversaries who cannot marshal the resources and technical sophistication to field their own constellations. Overall, widely diffused, demonstrably effective, and often unattributable tools are now available for pennies on the dollar. This is not an auspicious trend for an American way of war that prizes exquisite and expensive systems—nor does it promise the quick resumption of the era of free commercial navigation.
UNPLANNED OBSOLESCENCE
In 1980, U.S. President Jimmy Carter proclaimed the Carter Doctrine, identifying the Persian Gulf as a key American interest and declaring that any other actor’s attempt to gain control over this littoral zone would be met with force. This posture reflected U.S. oil and gas needs at the time. But over the past few decades, the shale revolution made the United States a net energy exporter, and the oil and gas transiting the Strait of Hormuz now flow overwhelmingly to Asia—to China as well as to the United States’ East Asian allies. The United States’ commitment to keep the strait open has become a free service to its chief strategic competitor and to allied customers who decline to share the cost—paid for with U.S. munitions, aircraft, ships, and other scarce resources that grand strategy dictates ought to belong in the Pacific.
The costs of commanding other contested waterways no longer add up, either. The United States’ strategic contest with China is not primarily military, but one unfolding mainly on economic, technological, and industrial battlefields. China has sought an advantage by dominating processing of critical minerals and the production of intermediate goods needed for technologies such as radars and refrigerators. U.S. resources need to be directed toward building industrial capacity rather than preparing for decisive naval battles against adversaries who prefer to play a different game. And as the price of controlling contested waters soars, the benefits of trying to do so diminish further.
China has invested heavily in an “undersea great wall.”
An all-out Chinese invasion of Taiwan or a direct military conflict with the United States within the next few years remains very unlikely. Such a decisive strike is not the logical choice when Beijing still holds many more valuable cards to play. China’s military is not its most potent weapon—that would be its demonstrated capacity to disrupt commerce without firing a shot. Using export controls and other regulations, newly implemented “blocking” measures that stack Beijing’s sanctions regime against that of the United States, and a litany of well-used coercive trade measures, China is challenging the U.S. Navy’s effort to secure free economic flows through the world’s waterways without initiating a decisive military showdown.
China has already become the world’s premier maritime power, if not yet its premier naval one. Over half of the world’s commercial vessels are now built in Chinese shipyards, and the country has the largest domestic and overseas port network; it became the world’s leading trading nation on the strength of its maritime industries, not its naval might. Sheer industrial scale, demand for resources, and manufacturing output have made Beijing the central player—and potential spoiler—in many vital global supply chains. This asymmetric economic threat undermines the efficacy of military methods of controlling the seas. Already, Beijing is forcing national and corporate leaders who do not wish to be excluded from the Chinese market to choose between it and Washington.
Lately, Chinese analysts have begun describing the bilateral relationship between their country and the United States as one of “strategic stalemate”—a competition that is unwinnable in the near term but will gradually favor China as America’s structural position erodes. If the Chinese approach is to price in extended peacetime confrontation rather than to force an outcome, then the responses that come most naturally to Washington—resorting quickly to military force and imposing sweeping tariffs and sanctions regimes—perversely undermine the free navigation and open economics that define the U.S.-led system.
A FUTURE OF FRAGMENTED OCEANS
The long-standing consensus in Washington that the Indo-Pacific is the strategic center of gravity in the twenty-first century remains correct. That is the sole theater in which the United States faces a potentially superior military and will likely be the locus of economic growth over the next several decades. Successfully balancing China and maintaining commercial access to the region will depend on whether U.S. policymakers can realign the country’s military strategy with economic realities. Long-term strategic competition requires more than preserving tactical advantages. The ultimate question is whether an open economic order upheld by free navigation is worth preserving and at what cost.
It is possible that Washington will be able to rebuild its shipyards and refill its magazines; design and build cheap, attritable defenses in the numbers that cheap, attritable weapons demand; compel its allies to pay their share for defense and carry a heavier operational load; and reestablish a degree of global military supremacy that restores freedom of navigation and vanquishes chokepoint challengers. That would be a welcome surprise. But the United States is swimming against structural currents that will remain strong for decades to come.
In the meantime, it has already become clear that maritime transit and the commerce that depends on it will not necessarily survive contact with the panoply of cheap tools now freely available to a wide range of actors. The tolling scheme that Tehran has begun imposing in the Strait of Hormuz is a sign of the fragmented and disorderly navigational regime that may arise in the near future, in which each chokepoint may require a separate peace for each trading state or even each vessel. The coming order will not be the closed seas of mercantilist nightmares but something older and more chaotic: gated seas, in which free passage is negotiated and purchased in a geopolitical marketplace rather than assured by legal right. Commercial shippers may need to price political risk into every route as they now price fuel costs and the weather. Routine chokepoint transits may require vessels to contract up-gunned private security forces or even naval convoys.
A growing proportion of global trade is carried on a shadow fleet.
Under such a dire scenario, commercial carriers would necessarily deal with whichever local power controls the local sea-lanes, paying a transit fee here, requesting an escort there, and simply taking the long way around a contested waterway when the arithmetic of operational risk demands it. Navies would revert to guarding their own flags and mount commerce raids on adversaries. The Trump administration’s emphasis on the Panama Canal and the Western Hemisphere is a step in this direction—and it may prove a realistic concession to the emerging structural reality.
This fragmentation is already underway—but the United States is needlessly hastening it. A growing proportion of global trade, especially in oil, is carried on a shadow fleet of opaque, uninsured tonnage that moves sanctioned cargo. If the United States turns to a strategy that swiftly reaches for punitive sanctions or tariffs instead of considering alternatives, it will drive even more ships into the dark and teach global commerce to bypass the dollar and the London-based insurance market.
Washington should instead apply sanctions surgically and concentrate naval power where the cost-benefit calculus still favors the defender rather than dissipate it everywhere all at once. And it should turn to legal frameworks to shore up trade that still operates by the rule of law, not as a cudgel against actors who will never fear such laws. The United States’ task is not to restore a freedom of navigation that rested on a command of the commons that it no longer enjoys (and was limited even in its heyday). It is, instead, to carefully husband its remaining advantages so that they can endure a while longer.
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