It’s hard to think of a time when the United States suffered a total defeat in a conflict, a setback so decisive that the strategic loss could be neither repaired nor ignored. The calamitous losses suffered at Pearl Harbor, the Philippines, and throughout the Western Pacific in the first months of World War II were eventually reversed. The defeats in Vietnam and Afghanistan were costly but did not do lasting damage to America’s overall position in the world, because they were far from the main theaters of global competition. The initial failure in Iraq was mitigated by a shift in strategy that ultimately left Iraq relatively stable and unthreatening to its neighbors and kept the United States dominant in the region.

Defeat in the present confrontation with Iran will be of an entirely different character. It can neither be repaired nor ignored. There will be no return to the status quo ante, no ultimate American triumph that will undo or overcome the harm done. The Strait of Hormuz will not be “open,” as it once was. With control of the strait, Iran emerges as the key player in the region and one of the key players in the world. The roles of China and Russia, as Iran’s allies, are strengthened; the role of the United States, substantially diminished. Far from demonstrating American prowess, as supporters of the war have repeatedly claimed, the conflict has revealed an America that is unreliable and incapable of finishing what it started. That is going to set off a chain reaction around the world as friends and foes adjust to America’s failure.

President Trump likes to talk about who has “the cards,” but whether he has any good ones left to play is not clear. The United States and Israel pounded Iran with devastating effectiveness for 37 days, killing much of the country’s leadership and destroying the bulk of its military, yet couldn’t collapse the regime or exact even the smallest concession from it. Now the Trump administration hopes that blockading Iran’s ports will accomplish what massive force could not. It’s possible, of course, but a regime that could not be brought to its knees by five weeks of unrelenting military attack is unlikely to buckle in response to economic pressure alone. Nor does it fear the anger of its populace. As the Iran scholar Suzanne Maloney noted recently, “A regime that slaughtered its own citizens to silence protests in January is fully prepared to impose economic hardships on them now.”

Some supporters of the war are therefore calling for the resumption of military strikes, but they cannot explain how another round of bombing will accomplish what 37 days of bombing did not. More military action will inevitably lead Iran to retaliate against neighboring Gulf States; the war’s advocates have no response to that, either. Trump halted attacks on Iran not because he was bored but because Iran was striking the region’s vital oil and gas facilities. The turning point came on March 18, when Israel bombed Iran’s South Pars gas field and Iran retaliated by attacking Qatar’s Ras Laffan Industrial City, the world’s largest natural-gas-export plant, causing damage to production capacity that will take years to repair. Trump responded by declaring a moratorium on further strikes against Iran’s energy facilities and then declaring a cease-fire, despite Iran’s not having made a single concession.

The risk calculus that forced Trump to back down a month ago still holds. Even if Trump were to carry out his threat to destroy Iran’s “civilization” through more bombing, Iran would still be able to launch many missiles and drones before its regime went down—assuming it did go down. Just a few successful strikes could cripple the region’s oil and gas infrastructure for years if not decades, throwing the world, and the United States, into a prolonged economic crisis. Even if Trump wanted to bomb Iran as part of an exit strategy—looking tough as a way of masking his retreat—he can’t do that without risking this catastrophe.

If this isn’t checkmate, it’s close. In recent days, Trump has reportedly asked the U.S. intelligence community to assess the consequences of simply declaring victory and walking away. You can’t blame him. Hoping for regime collapse is not much of a strategy, especially when the regime has already survived repeated military and economic pummeling. It could fall tomorrow, or six months from now, or not at all. Trump doesn’t have that much time to wait, as oil climbs toward $150 or even $200 a barrel, inflation rises, and global food and other commodity shortages kick in. He needs a faster resolution.

But any resolution other than America’s effective surrender holds enormous risks that Trump has not so far been willing to take. Those who glibly call on Trump to “finish the job” rarely acknowledge the costs. Unless the U.S. is prepared to engage in a full-scale ground and naval war to remove the current Iranian regime, and then to occupy Iran until a new government can take hold; unless it is prepared to risk the loss of warships convoying tankers through a contested strait; unless it is prepared to accept the devastating long-term damage to the region’s productive capacities likely to result from Iranian retaliation—walking away now could seem like the least bad option. As a political matter, Trump may well feel he has a better chance of riding out defeat than of surviving a much larger, longer, and more expensive war that could still end in failure.

Defeat for the United States, therefore, is not only possible but likely. Here is what defeat looks like.

Iran remains in control of the Strait of Hormuz. The common assumption that, one way or another, the strait will reopen when the crisis ends is unfounded. Iran has no interest in returning to the status quo ante. People talk of a split between hard-liners and moderates in Tehran, but even moderates must understand that Iran cannot afford to let the strait go, no matter how good a deal it thought it could get. For one thing, how reliable is any deal with Trump? He all but boasted of replicating the Japanese surprise attack on Pearl Harbor by approving the killing of Iran’s leadership amid negotiations. The Iranians cannot be sure that Trump won’t decide to attack again within a few months of striking a deal. They also know that the Israelis may attack again, as they never feel constrained from acting when they perceive their interests to be threatened.

And Israel’s interests will be threatened. As many Iran experts have noted, the regime in Tehran currently stands to emerge from the crisis much stronger than it was before the war, having not only retained its potential nuclear capacity but also gained control of an even more effective weapon: the ability to hold the global energy market hostage. When the Iranians talk of “reopening” the strait, they still mean to keep the strait under their control. Iran will be able not only to demand tolls for passage, but to limit transit to those nations with which it has good relations. If a nation behaves in a way that Iran’s rulers don’t like, they will be able to exact punishment merely by slowing, or even threatening to slow, the flow of that nation’s cargo ships in and out of the strait.

The power to close or control the flow of ships through the strait is greater and more immediate than the theoretical power of Iran’s nuclear program. This leverage will allow the leaders in Tehran to force nations to lift sanctions and normalize relations or face penalties. Israel will find itself more isolated than ever, as Iran grows richer, rearms, and preserves its options to go nuclear in the future. It may even find itself unable to go  after Iran’s proxies: In a world where Iran wields influence over the energy supply of so many nations, Israel could face enormous international pressure not to provoke Tehran in Lebanon, Gaza, or anywhere else.

The new status quo in the strait will also occasion a substantial shift in relative power and influence both regionally and globally. In the region, the United States will have proved itself a paper tiger, forcing the Gulf and other Arab states to accommodate Iran. As the Iran scholars Reuel Gerecht and Ray Takeyh wrote recently, “The Gulf Arab economies were built under the umbrella of American hegemony. Take that away—and the freedom of navigation that goes with it—and the Gulf states will ineluctably go begging to Tehran.”

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They will not be the only ones. All nations that depend on energy from the Gulf will have to work out their own arrangements with Iran. What choice will they have? If the United States with its mighty Navy can’t or won’t open the strait, no coalition of forces with just a fraction of the Americans’ capability will be able to, either. The Anglo-French initiative to police the strait after a cease-fire is a bit of a joke. French President Emmanuel Macron has made it clear that this “coalition” will operate only under peaceful conditions in the strait: It will escort ships, but only if they don’t need an escort. Yet with Iran in control, the strait is not going to be safe again for a long time. China presumably has some influence over Tehran, but even China cannot force open the strait by itself.

One effect of this transformation may be an expanding great-power naval race. In the past, most of the world’s nations, including China, counted on the United States to both prevent and address such emergencies. Now the nations in Europe and Asia that depend on access to the Persian Gulf’s resources are helpless against the loss of energy supplies that are vital to their economic and political stability. How long can they tolerate this before they start building their own fleets, as a means of wielding influence in an every-nation-for-itself world where order and predictability have broken down?

The American defeat in the Gulf will have broader global ramifications as well. The whole world can see that just a few weeks of war with a second-rank power have reduced American weapons stocks to perilously low levels, with no quick remedy in sight. The questions this raises about America’s readiness for another major conflict may or may not prompt Xi Jinping to launch an attack on Taiwan, or Vladimir Putin to step up his aggression against Europe. But at the very least America’s allies in East Asia and Europe must wonder about American staying power in the event of future conflicts.

The global adjustment to a post-American world is accelerating. America’s once-dominant position in the Gulf is just the first of many casualties.