Wars often go wrong in unexpected ways. Even well-planned operations can be derailed by surprise events, equipment failures, bad weather, or bad luck. But the disaster that followed President Donald Trump’s decision to attack Iran on February 28 was not a surprise. War-gamed and red-teamed dozens of times over decades, the risks of the campaign were well-known and obvious. 

Still, the war’s outcome has been worse than the most pessimistic predictions. Three months into what the Trump administration has called an “excursion,” the initial assessment that Operation Epic Fury was a “tactical success but strategic failure” appears too generous. After all, neither strategic nor tactical goals were achieved. The United States did not replace the Iranian regime with new, moderate leaders. It failed to seize Iran’s highly enriched uranium or eliminate Iran’s nuclear program. Worse, most reports suggest Iran has retained much of its military capacity, including access to large portions of its missile and drone stockpiles. Finally, the war has created a new, bedeviling problem. The Strait of Hormuz, once the passageway for 20 percent of the world’s oil and liquified natural gas, remains effectively closed.

No matter how the war ends, the costs of the latest U.S. military adventure in the Middle East will be steep and the geopolitical consequences irreversible. The next generation of U.S. leaders will face a stark reality. The United States, which for decades has made decisions based on what policymakers thought America should do, will be forced to consider what the United States can do. The change will have major implications for the United States, but also for U.S. allies who have come to depend on American security guarantees and for the international community that relies on the United States for provision of global security goods, like freedom of navigation. 

It will take time for the American imperial project to disappear for good, but from this point, U.S. retrenchment is inevitable. In 20 years, the world will look back on this moment as a turning point: the beginning of the end of American empire.

President Trump has declared victory in the Middle East. But to anyone with eyes, his rosy prognosis does not match the reality. The most obvious evidence of the American failure is the continued closure of the Strait of Hormuz (which was open before the war), despite several attempts by the U.S. Navy to get traffic moving again through the narrow chokepoint. Although a small number of tanker and cargo ships have successfully transited the strait in recent weeks, most of the traffic remains stalled due to the security concerns of ship owners, captains, and their crews.

Away from Hormuz, the inability of the United States and Israel to suppress Iranian missile and drone attacks is perhaps the war’s biggest disappointment. Ambitious U.S. goals like regime change and eliminating Iran’s nuclear program were never achievable using military force alone, but destroying Iran’s ability to produce and launch missiles and drones that could be fired at regional neighbors seemed attainable. Recent reporting, however, suggests that even this objective has slipped through the U.S. military’s fingers; Iran appears to retain as much as 70 percent of its pre-war missiles and launchers and access to 30 of its 33 missile sites. Iran’s ability to manufacture drones also seems robust. That Iran was able to sustain a consistent rate of fire after the war’s opening days is further evidence that the damage inflicted by the U.S. military was somewhat less devastating than suggested by the Pentagon and the White House.

The results of the war, then, are dismal. The costs of the military failure, on the other hand, are significant—and not only in monetary terms. 

The Pentagon has told Congress that the first 40 days of war, up until the April ceasefire, cost $29 billion, but this is almost certainly a vast underestimate. The Department of Defense (DoD) has been ambiguous about what is included in this estimate, but at the very least it does not account for the massive damage to U.S. military infrastructure or the full costs of replacing U.S. military aircraft and other equipment lost in the conflict. The full price tag is likely to be twice as high as DoD’s early tally. 

Most up-to-date assessments suggest that at least 16 U.S. military installations across eight countries—most of the U.S. military positions in the region—suffered severe damage. For many of these sites, the damage incurred was so extensive as to render the facility effectively unusable for military operations. The cost of reconstituting these bases and hardening infrastructure across the region against renewed conflict will be high, but the total is difficult to estimate since the U.S. government is still limiting access to open-source satellite data in the region. Iranian missile and drone strikes also successfully targeted dozens of U.S. sensors and radars across the Middle East, including those underlying U.S. regional air defense and early warning networks. Forty-two military aircraft, including an E-3 AWACS, four F-15s, and seven air tankers, were also damaged or destroyed. Replacing these assets will require tens of billions in additional spending.

Costs to long-term military readiness are hard to measure and surely not counted in the Pentagon’s estimate, but they are worth considering anyway. In addition to wear and tear to equipment and personnel caused by the war, the loss of aircraft and air defense platforms and the depletion of U.S. missiles and air defense interceptor stockpiles will affect U.S. preparedness for future military operations. Some estimates suggest the United States has burned through 1,000 Tomahawk missiles, nearly 50 percent of its Patriot and THAAD stockpiles, and significant portions of advanced stand-off weapons like PRSM and JASSM missiles. 

The constraints on U.S. military power created by these shortages will be consequential and enduring. In congressional testimony, Secretary of Defense Pete Hegseth admitted that it would take years to replenish the missiles expended in Iran. During this time, American strategic flexibility will be limited. For example, leading experts now assess that the U.S. military arsenal is not sufficient to support a defense of Taiwan, long considered the highest priority contingency for American military planners. To put this more bluntly, if China were to attack Taiwan tomorrow, the United States might be forced to watch on the sidelines. The same is probably true of a major conflict in Europe.

As seriously, the problems facing a diminished U.S. military will be contagious, affecting the rearmament efforts of U.S. allies across regions. As our stockpiles are rebuilt, the United States will have to divert most defense production to its own military, reducing what is available for sales to U.S. allies and partners who have based their rearmament plans on such weapons purchases. Already, European NATO members are hearing that shipments of much-needed missiles and other weapons are being delayed indefinitely. Allies in Asia have been similarly warned. Japan’s shipments of Tomahawk missiles, for instance, are likely to arrive late, as are most weapons in recent Taiwan arms packages. 

For many of these allies, such delays are unsustainable. In Europe, for instance, there is talk of focusing more heavily on indigenous production or shifting orders to other suppliers such as Israel, Turkey, or South Korea. In some ways, allied assessments that the United States is an unreliable partner are a good thing, pushing countries that have long been dependent on the United States firmly and finally in the direction of independence and self-sufficiency. But, for the United States, it will be a dramatic change that contributes to a gradual erosion of its position of global military dominance.

Beyond military costs, there is the economic damage caused by the conflict, which is outside the Pentagon’s purview but real and serious nonetheless. The economic losses caused by disrupted trade are likely to be massive, measured in slowed economic growth and lost corporate profits and national income. For the United States, the effects of higher oil prices and inflation for American consumers are the biggest concerns. And of course there are also the opportunity costs, that is, the U.S. government investment in domestic programs that will now be delayed and foregone to support higher military budgets. 

The bottom line is this: The war has not made Americans safer, but they will be paying for it for decades anyway.

The U.S. failure in Iran is unprecedented in its effect on American geopolitical standing, but the military mistakes made in Iran are themselves not unique for the United States. Like previous ill-fated U.S. military campaigns, the Iran War began with unclear, broad goals that could never have been achieved using military force alone. Also as in previous wars, the stakes for the United States were considerably lower than they were for the adversary, a fact that set the United States up for failure from the start. For Iran, the stakes of the current conflict are existential and willingness to endure pain seemingly infinite, while for the United States, the interests at stake are limited at best. Iran was never close to having a nuclear weapon, and, despite its aggressive rhetoric, Tehran posed no real threat to U.S. national security. Finally, American political and military leaders once again made the error of believing their goals in Iran could be accomplished quickly, and then failed to develop a strategy or theory of victory for an extended campaign.

In the past, America’s overwhelming military and economic advantages have offered Washington a generous margin of error to absorb these repeated military disappointments. Today, this cushion has evaporated. Combined with the cumulative effect of decades of U.S. overextension, China’s rapid military development, and the democratization of military power to weak states and non-state groups, the war in Iran has erased much of the remaining U.S. military edge. Forty days of fighting plus six weeks of blockade have not only drained stockpiles but revealed systemic weaknesses in the American way of war and clear limits on American military power. For the first time in decades, the U.S. military looks beatable—and is.

First, the vulnerability of U.S. bases, ground-based air defense, and military aircraft during the war has significant implications for the sustainability of U.S. military commitments. U.S. operations in any sort of Indo-Pacific contingency would depend heavily on forward bases to project airpower, to support intelligence, surveillance, and reconnaissance, and to manage logistics and combat support. Pentagon plans also place faith in the ability of ground-based air defense to protect U.S. military infrastructure, personnel, and aircraft. If U.S. bases in the Middle East cannot withstand attacks from Iran, could those in Asia survive in a conflict with the much more militarily capable Chinese military? Would U.S. air defense networks, which were degraded so quickly by Iranian drones, remain viable in a contingency in Asia? The answer to both questions is probably no. 

At the same time, the war has underscored the limits of what can be accomplished with “stand-off” attacks (those executed from a distance). American air and naval strikes achieved only narrow success against Iranian military targets, despite Iran’s limited defenses. Iran was able to protect much of its military infrastructure and capabilities and to innovate in areas like air defense throughout the conflict. Similar attacks on Chinese infrastructure are likely to be even less effective, especially if U.S. air and naval forces must operate from beyond the second island chain to avoid Chinese missiles. 

U.S. failures in other areas are also revealing. The United States has been unable to reopen the Strait of Hormuz using military force, though some might contend that it could if it were willing to accept the high escalation risks and costs of such a maneuver. And the sieve-like nature of the U.S. counter-blockade should raise a red flag for those who argue that the United States could cut off access to the Strait of Malacca or impose embargos on Chinese ports in case of a war in Asia. Finally, U.S. ground forces have largely failed to counter Iran’s drone threat and are unable to match it with capabilities of their own. Together with observations from the war in Ukraine, U.S. Army leaders have already acknowledged that they will have to radically change how they think about maneuver warfare as they plan for future contingencies, including those to support NATO allies in a ground war in Europe.

The key takeaway is that U.S. military power simply doesn’t reach as far or have the staying power that it used to. Just as seriously, the war in Iran suggests that the insolvency of the current U.S. military position is systemic and strategic, not simply a question of lack of funds or insufficient magazine depth. A $1.5 trillion defense budget or investment in the defense industrial base cannot solve these problems. Instead, the United States will be forced to reevaluate and reduce its global commitments in a way that it has not in the past.

Writing in Foreign Affairs earlier this year, A. Wess Mitchell, an alumnus of the first Trump administration, acknowledged that the United States is overextended. He calls for a strategy of consolidation, in which the United States would shed burdens in peripheral theaters—namely the Middle East and Europe—and revitalize the engines of American military and economic power by investing in its defense industrial base and rebalancing trade relationships with major partners like China. He suggests that consolidation is an alternative to retrenchment, on the assumed premise that the foundations of American military power remain solid, needing only a reset.

Unfortunately, after the war with Iran, this option no longer appears realistic. The gap between U.S. means and its currently articulated ends is simply too vast and structural to be addressed with industrial investments or new trade deals. The fundamental assumption of consolidation, that the engines of American military power are still viable, is now in doubt. U.S. manufacturing capacity has failed to rebound despite significant investment, and with a national debt that exceeds 100 percent of GDP and rising energy prices, American economic endurance is sputtering. There is little chance the United States can produce enough missiles fast enough or reboot its shipbuilding capacity sufficiently to sustain even a fraction of its current portfolio of global commitments. Moreover, after expending so much military power on the war in the Middle East, it is not clear that there is much left for the United States to consolidate and redirect to the theaters that Mitchell defines as higher priorities, including Asia and the Western Hemisphere. 

Now retrenchment is the only choice for the United States. But the news is not all bad. America’s military dominance is waning, but the country continues to have notable advantages in most theaters over any possible rival. Even in Asia, where Washington faces a peer challenger, China’s military is not capable of driving the United States out of the region entirely. Decisionmakers, therefore, have a degree of flexibility in terms of what commitments to keep and which to surrender. Retrenchment, in other words, can be managed.

In making tough choices, U.S. policymakers should adopt a narrow definition of national interests—just two, in fact: defending the homeland and ensuring access to key economic markets. Such a definition would allow for a substantial reduction of U.S. military forces based abroad. The United States does not need military bases and deployments in Europe or the Middle East to protect these interests. There is no true hegemonic challenger in either theater, and the threats that exist to the United States can be addressed with periodic deployments of air and naval power, better missile defense of the homeland, and a more robust global economic strategy. Managed retrenchment would also demand a narrowing of U.S. security guarantees. Even if the United States remains in NATO, it should return to a literal interpretation of Article 5 that reduces U.S. obligations and should give up all security commitments in the Middle East—a region that has brought only headaches. 

In Asia, a managed retrenchment strategy would similarly reduce American posture and security guarantees, though perhaps initially to a lesser extent. Unsustainable positions, like the U.S. policy of strategic ambiguity on Taiwan, should be dropped. Washington should state clearly that it will not defend Taiwan, a move that would reduce the risk of a war with China that at this point the United States is unprepared to fight. The United States should drop other necessary alliance commitments, including those to Thailand, the Philippines, and South Korea, while narrowing its commitment to Japan. This would allow for a repositioning of U.S. military forces in Asia away from China’s coast toward northern Japan and the second island chain—sufficient to defend U.S. access to markets and trade routes. 

These changes in posture and alliance commitments would amount to a massive transformation of American foreign policy, but the result would be a sustainable military position, consistent with U.S. capabilities and resources and tailored to protecting U.S. interests. 

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Those hoping to cling to U.S. dominance—many of the same people who see the Iran War as a success that requires just a few more weeks of bombing—will abhor these recommendations, pushing efforts to sustain the status quo. But such a delay will close the opportunity for managed retrenchment and thrust the United States into a reality in which retrenchment will be mandatory and required, forced on the United States.

Forced retrenchment could occur in many ways, but they will all feel like a retreat. Resource constraints could require the United States to reduce commitments, close bases, and shrink force structure. Defeat in a military conflict, provoked by unsustainable deployments, vulnerable bases, and chronic overextension, could also force U.S. pullback. In any of these scenarios, involuntary reductions in U.S. military posture could compromise U.S. interests. Under duress, policymakers will lose the ability to control the pace or location of changes in U.S. military footprint. Instead, these decisions might be made by U.S. adversaries, fiscal pressures, or external constraints that leave Americans less safe and less well-off over the long run.

Today, the U.S. foreign policy debate is driven by the aftermath of the war with Iran. An agreement to end the root causes of the conflict has yet to be signed, but policymakers now need to start talking about what comes next. The war has revealed the fragility of U.S. military power and the clear limits on what it can accomplish in the modern era. Instead of maintaining the fiction that after the war U.S. foreign policy can return to normal, policymakers should face reality: The period of U.S. military dominance—and of American empire—is over. The resulting future will be less comfortable for the United States, but its changes are overdue and its challenges manageable. With the right moves today, American retrenchment can leave the United States, and the world, better off.