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One thing is certain about the widely anticipated U.S. war on Iran: If it happens, it won’t include an occupation of the country. The United States has been sending aircraft carriers and support equipment to the Gulf, not expeditionary ground forces for an invasion, and there has been no public evidence of any planning for a long-term presence in Iran. If U.S. President Donald Trump has been consistent about one thing in the region, it’s the need to avoid another Iraq-style occupation, which he’s described as a “big fat mistake.” As with the capture of Venezuelan President Nicolàs Maduro in January, the killing of Islamic Revolutionary Guard Corps (IRGC) commander Qassem Soleimani in 2020, and Israel’s decapitation strike against Hezbollah leader Hassan Nasrallah in 2024, the United States would likely target top leaders in Iran along with the regime’s repressive apparatuses, and then let the cards fall where they may.

So, where will they fall? Iran, of course, can see the same things we can and is unlikely to be taken by surprise. Tehran remembers well how the United States used scheduled negotiations as a smokescreen to entice it to lower its guard ahead of a surprise attack last June, and it is unlikely to fall for the same ruse again. It has fortified its positions in anticipation. Security forces are fully mobilized and deployed after the brutal suppression of recent protests, and they have spent months assiduously rooting out suspected Israeli intelligence assets (and no doubt sweeping up many innocents in the process). Israel’s remarkable success in targeting senior Iranian officials last June speaks to the degree that Iranian intelligence has been penetrated and suggests that the country’s supreme leader, Ayatollah Ali Khamenei, and its senior leaders should not sleep easy. They may well be killed, but it won’t be for lack of preparation.

One thing is certain about the widely anticipated U.S. war on Iran: If it happens, it won’t include an occupation of the country. The United States has been sending aircraft carriers and support equipment to the Gulf, not expeditionary ground forces for an invasion, and there has been no public evidence of any planning for a long-term presence in Iran. If U.S. President Donald Trump has been consistent about one thing in the region, it’s the need to avoid another Iraq-style occupation, which he’s described as a “big fat mistake.” As with the capture of Venezuelan President Nicolàs Maduro in January, the killing of Islamic Revolutionary Guard Corps (IRGC) commander Qassem Soleimani in 2020, and Israel’s decapitation strike against Hezbollah leader Hassan Nasrallah in 2024, the United States would likely target top leaders in Iran along with the regime’s repressive apparatuses, and then let the cards fall where they may.

So, where will they fall? Iran, of course, can see the same things we can and is unlikely to be taken by surprise. Tehran remembers well how the United States used scheduled negotiations as a smokescreen to entice it to lower its guard ahead of a surprise attack last June, and it is unlikely to fall for the same ruse again. It has fortified its positions in anticipation. Security forces are fully mobilized and deployed after the brutal suppression of recent protests, and they have spent months assiduously rooting out suspected Israeli intelligence assets (and no doubt sweeping up many innocents in the process). Israel’s remarkable success in targeting senior Iranian officials last June speaks to the degree that Iranian intelligence has been penetrated and suggests that the country’s supreme leader, Ayatollah Ali Khamenei, and its senior leaders should not sleep easy. They may well be killed, but it won’t be for lack of preparation.

Whether through a deal or war, Trump’s goal seems to be to decisively end the United States’ decades-long struggle with Iran. But decisive victories tend to be elusive. If the bombing achieves success without immediate catastrophic consequences, then Trump will declare victory and move on to the next thing. But the Iranian people and the Middle East as a whole will be living with the carnage for years to come. Even the most devastating air campaign against Iran’s regime will prove no more enduring a victory than former U.S. President George W. Bush’s infamous declaration of “mission accomplished” in Iraq.

A bombing campaign that does not take out the regime’s leadership would probably look like a replay of Israel’s 12-day war with Iran last summer, destroying some of Iran’s nuclear facilities and degrading the regime’s repressive capacity while killing some number of leaders. The long-standing intelligence assessment that a bombing campaign would set back the Iranian nuclear program by a couple years at best has been a key inhibiting factor in earlier rounds of Iran war fever. There is no particular reason to think that this time would be different. Iran’s leaders seem to be anticipating such an attack and preparing to contain the consequences.

Such an attack may well prove helpful to the regime. The leadership’s survival would likely inhibit another wave of anti-regime protests, though the underlying drivers of discontent make it unlikely that the pause would prove especially enduring. Iran could then expect more Western sanctions, which would intensify societal immiseration and degrade the regime’s repressive capacity but do little to inhibit its regional policies or the rebuilding of its nuclear and missile programs. In other words, the destruction and risk would reset the long-running status quo, one in which the IRGC and regime allies have long thrived at the expense of everyone else.

But suppose the United States actually does kill Khamenei and cause the regime to fall while refusing to play a role in the post-regime change occupation. What would Iran actually look like and how might it affect the region? Most analysis ends with the regime’s collapse, assuming that anything would be better than the Islamic Republic or that the catastrophe will consume all. But the more likely outcome is in the messy middle.

There are four likely scenarios. The emergence of a democratic republic will be what many Iranians prefer, but it is the least likely outcome of a regime change triggered by airstrikes alone. Iran would be left with an institutional vacuum, economic and infrastructural devastation, and no meaningful assistance from abroad. Trump could not care less about democracy, with exhibit A being Venezuela. He has no day-after plan for Iran, and most of the U.S. government personnel who might have once formulated such a plan have long since been fired.

Some Americans, Israelis, and Gulf leaders may prefer the restoration of Shah Reza Pahlavi, but placing him on the throne and protecting him would likely require significant external military assistance. Nobody wants to provide that assistance, and few Iranians in Iran (as opposed to the diaspora) are interested. Pahlavi’s Israeli allies and vociferous American lobbyists will push to give him a chance, but a Tehran version of Baghdad’s Green Zone will not be popular amid the carnage of a post-war Iran.

State failure and collapse into civil war is a more likely outcome than either democracy or a monarchical restoration. There is an important policy divergence among outside players on this question. Israel may well be just fine with a divided, weak, and fragmented Iran consumed by civil war and ethnic splintering. But the United States does not seem to share that aspiration. Its embrace of Ahmed al-Sharaa’s regime in Syria (and its cynical elevation of Maduro’s vice president in Venezuela) suggests that it prefers stability under whatever regime is available. Above all, the Gulf states want to avoid another destabilization in the Middle East at all costs, with all the refugees, terrorism, and instability that it would entail. Their top priority at this point is to avoid a collapsed Iran dragging the rest of the region down into the hellmouth, destabilizing Iraq and Syria, as well as potentially disrupting oil shipping.

The most likely outcome of successful regime change in Iran is a takeover by the IRGC, which would be the best armed and most powerful force in a chaotic transitional environment. An Iranian military regime would likely remain sanctioned and unstable, and it might draw on nationalist rage against the U.S. attack to consolidate its control. A key question would be whether the United States would actually modify its targeting strategy to keep state repressive capability intact to avoid the worst-case scenario of state failure—even if it comes at the expense of the recently brutalized protestors, who yearn for something better.

An IRGC-led regime might have unintended consequences. The threat posed by Iran’s Islamic Republic is what holds the United States’ Middle East order together. The threat is manageable but threatening enough to justify the need for strong ties to the United States and cooperation with Israel. An Iranian regime that is nationalist and competent but not revolutionary might not be threatening enough to sustain that logic and could accelerate the decoupling of Saudi Arabia and other regional powers from an increasingly erratic and unreliable United States.

Such a regime may ironically come to resemble Saudi Arabia under Crown Prince Mohammed bin Salman: brutally repressive and authoritarian but opening up socially and eager for international investment. In other words, the best-case scenario after all the death and destruction might be a nationalist, authoritarian, and emboldened Iranian regime that is liberated from the unpopular trappings of an aging supreme leader and religious establishment. Gulf leaders might be willing to live with that. Can Washington?

This post is part of FP’s ongoing coverage of the Trump administration. Follow along here.