What Comes After the 12-Day War

By Suzanne Maloney
Vice President of the Brookings Institution

Foreign Affairs

Rarely in modern history has a military offensive been as loudly and persistently foreshadowed as the June 2025 Israeli and American strikes on Iran’s nuclear program. For more than three decades, leaders in Tel Aviv and Washington have issued stark warnings about the Islamic Republic’s nuclear ambitions and activities, and five American presidents have pledged to prevent Tehran from crossing the threshold of nuclear weapons capability.

Despite this forewarning and the signals of imminent preparations, Israel’s initial attack on Iran’s nuclear infrastructure—capped by a brief but decisive U.S. intervention—still shocked Tehran and much of the world. The element of surprise helped facilitate the stunning success of the operation, which briskly decapitated Iran’s military leadership, secured Israeli air superiority over Iranian territory, blunted Iran’s ability to retaliate, and inflicted substantial damage on the crown jewels of the country’s nuclear infrastructure.

The virtuoso execution of the operation and the absence of an effective counterattack by Tehran or its once fearsome network of regional proxies led to another surprise: the rapid denouement to the crisis via an American-imposed cease-fire on the conflict’s 12th day. In less than two weeks, the joint U.S.-Israeli effort accomplished what many had thought impossible, delivering an extraordinary setback to Iran’s nuclear program without igniting a wider regional conflagration. Tehran’s retaliatory missile attacks on Israel, as well as a performative strike on the U.S. airbase in Qatar, were showy but ineffectual. For many in Washington, the result seemed to exorcise the ghosts of failed or frustrated American military interventions in the Middle East over the past four decades.

The remarkable outcome compounded a broader collapse in Tehran’s strategic posture that had begun the preceding year, when Israel decimated the regime’s most valuable asset—the Lebanese militant group Hezbollah—and Iran’s foothold in Syria crumbled alongside Bashar al-Assad’s regime. As the June conflict erupted, Iran’s ostensible strategic partners in Moscow and Beijing offered nothing more than mild condemnations.

Ever since 1979, when a revolutionary Islamist regime came to power in Tehran, Washington and its allies have sought to restrain Iran. That effort has now reached a milestone: the Islamic Republic is weaker and more isolated than it has been at any point in the past two decades. It is no longer able to impose its will across the region or even to defend its own borders and people. Now that the giant has been wrestled to the ground, there is a temptation to pronounce the mission accomplished. That would be premature: Iran is down but not yet out.

The grave dangers posed by the Islamic Republic persist, and a rolling conflict could transform or even amplify them. Despite grievous losses and the humiliation of its rout at the hands of its foremost adversaries, the revolutionary regime retains a coercive grip on power. Its nuclear infrastructure is wrecked but by no means wholly eradicated. The twin exigencies of vengeance and regime survival may sustain Tehran’s violent and destabilizing impulses at home and across the region and extinguish any residual uncertainty about the merits of a nuclear deterrent.

As the writer James Baldwin once remarked, “The most dangerous creation of any society is the man who has nothing to lose.” That description might now apply to the men who preside over the ruins of Iran’s revolutionary system. With their proxy network degraded, their air defenses demolished, and their great-power alignments exposed as hollow, the debilitated guardians of the Islamic Republic require new tools to keep the wolves at bay. It is difficult to predict with confidence how factional dynamics will evolve in the aftermath of the regime’s humbling; further surprises may be in store. But there can be little doubt that the most powerful set of players in Tehran will seek to reconstitute the remnants of its nuclear program and reassert the regime’s dominance over Iranian society.

Even in its humbled state, a recalcitrant Tehran will remain a dangerous actor and a powerful source of instability and uncertainty in the region. In the modern Middle East, a resounding blow against a troublemaker has rarely resulted in conciliation, capitulation, or even durable de-escalation. Any consensus around the shape of a new regional order among the powers left standing—Israel, Saudi Arabia, and Turkey—has been fractured by the war in Gaza and will be further strained by an unresolved conflict with Iran.

Ultimately, by resorting to military force, Israel and the United States may have accelerated the very outcome they sought to forestall: an even more repressive and adversarial Islamic theocracy with a bomb in the basement and a score to settle in its backyard. And U.S. President Donald Trump, who has consistently campaigned against Washington’s long, costly interventions in the Middle East, might find his preferred exit strategy reduced to just another operational success that fails to yield a stable political equilibrium.

IRAN’S NEW CALCULUS

Iran’s nuclear program originated as a civil energy project in the 1970s by the U.S.-aligned, prestige-obsessed Pahlavi monarchy, despite American misgivings about the potential for proliferation. After the 1979 revolution, Iran’s new rulers saw the program as a vestige of Western influence and largely shuttered it. But some nuclear research continued, and after the fledgling theocracy was invaded by Saddam Hussein’s Iraq in 1980 and became enmeshed in a brutal war of attrition, investment in nuclear infrastructure reemerged as a convenient source of cheap energy, power projection, and deterrence against future hostilities.

Over the next four decades, the Islamic Republic assembled an industrial-­scale nuclear program that steadily came to define the regime’s identity and its tormented relationship with Western powers. Iran’s post-revolutionary nuclear pursuits initially emphasized technological self-sufficiency and domestic capabilities, but by the late 1990s, they had expanded to include an extensive clandestine effort to acquire weapons capability. With a front-row seat to the 1981 Israeli attack that partially destroyed Iraq’s Osirak nuclear reactor, Iran’s leadership was acutely sensitive to the risks, and as the George W. Bush administration launched the 2003 U.S. invasion of Iraq, Tehran paused its work on weaponization.

Such caution characterized Tehran’s approach from the start. Iranian leaders frequently invoked a religious injunction against the use of weapons of mass destruction that Supreme Leader Ali Khamenei issued in 2003. Nevertheless, as Akbar Hashemi Rafsanjani, who served as Iran’s president from 1989 to 1997, acknowledged in 2015, “It never left our mind that if one day we should be threatened and it was imperative, we should be able to go down the other path.” After Iran and Israel engaged in direct attacks on each other in April 2024 and then again in October of that year, even relatively pragmatic voices within the ruling system began to publicly dangle the possibility of a nuclear breakout. “If an existential threat arises, Iran will modify its nuclear doctrine,” former Foreign Minister Kamal Kharrazi insisted in November 2024. “We have the capability to build weapons and have no issue in this regard.”

In the wake of the joint U.S.-Israeli assault in June, an atomic insurance policy may become exponentially more desirable for the Islamic Republic. Iran’s leadership could now double down on its nuclear bet by attempting to salvage the wreckage and launch an all-out effort to acquire a weapon—but more quietly this time. Its ability to do so would depend on the state of Iran’s nuclear infrastructure, which suffered extensive damage. The Israeli strikes also eliminated a key cadre of nuclear scientists who designed and oversaw the program. Although the extent of the damage is still being assessed, initial readouts from the International Atomic Energy Agency (IAEA) and from independent experts suggest that Iran’s enrichment capability has been heavily degraded or even fully incapacitated. Still, some experts have suggested that Tehran could recoup and rebuild its losses over months or a few years and that core components, such as its stockpiles of enriched uranium, and centrifuges that were not installed at the time of the attack, may have survived the strikes and could be redirected toward a crash program to develop a nuclear weapon within a year.

Iranian efforts to reconstitute its nuclear program would happen without any formal oversight and in contravention of the country’s continuing official commitments under the Nuclear Nonproliferation Treaty. During the brief life of the Joint Comprehensive Plan of Action, the nuclear deal Iran struck with the United States and other powers in 2015, Iranian leaders offered some transparency in exchange for being allowed to preserve the program and obtaining relief from crippling international economic sanctions. But after Trump withdrew the United States from the deal in 2018, Tehran began gradually but steadily reneging on its end of the bargain, including by limiting access to some safeguarded facilities.

After the recent attacks, Iranian politicians and commentators suggested that the country’s earlier cooperation with the IAEA allowed Israel and the United States to gather targeting data. The Iranian parliament suspended cooperation with the agency, prompting the agency to hastily remove its remaining inspectors from Iran, for their own protection. For the near term or even longer, there will be no one to provide independent verification of the status of Iran’s nuclear program.

In the past, Iran relied on caution and transparency to protect its nuclear investment and, by extension, the survival of its regime. The June attacks have likely flipped the script; in the wake of the attacks, Tehran may be prepared to assume greater risk to maintain its nuclear options and to ensure that the pursuit remains concealed from the world. This shift is compounded by the erosion of the forward defense that Iran’s proxy network used to provide. With Israel’s success in neutralizing Hezbollah and the toppling of Iran’s ally in Syria, Iranian leaders may conclude that the nuclear option is their only option.

RALLY ROUND THE FLAG

Tehran’s approach to its nuclear program will be shaped by how its domestic politics evolve in the aftermath of the Israeli and American strikes. Iranian leaders are acutely sensitive to the possibility of internal instability. The news outlets that serve as regime mouthpieces have cast the outcome of the 12-day war as a victory: the ruling system held firm and lived to fight another day. The initial fallout from the conflict has reinforced the regime’s grip, and its leaders are applying tactics they have honed during prior crises to ensure stability in what they expect to be an even more volatile time ahead. Anticipating further hostilities, the regime preemptively cracked down on critical voices. Dissidents, including Narges Mohammadi, who was awarded the Nobel Peace Prize in 2023, have been threatened; hundreds of others have been detained, including on espionage charges; and Iran’s hard-line judiciary is fast-tracking trials for accused collaborators with Israel. Around half a million Afghans who had taken refuge in Iran in the course of the long war in their country were forced to repatriate under duress as the hunt for Israeli collaborators accelerated a deportation campaign that began earlier in the year.

Although U.S. officials insisted that the strikes were not intended to precipitate regime change, the Israeli game plan may have been more ambitious. The Washington Post reported that senior Iranian officials had received anonymous phone calls in Persian thatencouraged them to abandon the regime or risk death. The Tehran Times, an English-language news outlet published in Iran, reported that Israel had botched a broader attempt to decapitate the regime by killing Iran’s president, the speaker of the parliament, and a host of other officials.

Instead of toppling or disabling the current regime, the Israeli strikes appear to have stirred Iranians’ enduring attachment to their nation. Although many Iranians are deeply disillusioned with the regime, as evidenced by recurring spasms of public dissent, a widespread yearning for a better future and more responsible leaders coexists alongside a deep well of nationalism and resentment toward foreign antagonists. The absence of any political movement or charismatic figure to mobilize an inchoate opposition leaves the Islamic Republic as the only game in town.

Although the conflict was brief, the bombardment spanned 27 of the country’s 31 provinces and was intense, disruptive, and terrifying for Iranians. Thousands of residents fled Tehran after Trump issued a middle-of-the-night evacuation demand via social media. Communities came together in solidarity to help their fellow citizens. In some cases, symbolic Israeli strikes backfired. For instance, an attack on the notorious Evin prison in Tehran, where many political dissidents are detained, was presumably intended to embolden regime critics. Instead, it sparked popular outrage, including from prominent opposition figures, because the victims included the family members and lawyers of inmates.

Regime officials took solace in the popular response. As the veteran government official and negotiator Ali Larijani boasted in a lengthy interview with an Iranian news outlet, “Contrary to the enemy’s expectation of internal division and rift, the Iranian nation, regardless of political affiliations, showed unparalleled unity. Even some opponents of the government stood behind Iran.” The current leadership is experienced at stoking nationalist sentiments, just as it did during the Iran-Iraq War in the 1980s. Shortly after the 12-day war concluded, Khamenei emerged from his bunker to lead a solemn religious ceremony. The event began with a rendition of “Ey Iran,” a pre-revolutionary patriotic anthem, with its lyrics modified to incorporate religious motifs. A mute Khamenei presided, appearing dazed or overwhelmed, before a raucous crowd.

Khamenei’s public absence throughout the conflict and his raspy speech in its aftermath have prompted speculation about his health and the theocracy’s continuity of leadership. His presence at the helm is fading, and the mandarins of the system may use the crisis as a dress rehearsal to secure the passing of the torch to the next generation when the transition finally occurs. As the jockeying for influence intensifies, the recent round of attacks will reinforce the symbiotic relationship between the regime’s clerical power structure and the military. Their teamwork in navigating the war and the uncertainty following it is meant to signal to the regime’s internal and external opponents that the system will endure under pressure and prevent any challengers. This will likely dampen the prospects for significant political change after Khamenei’s death.

TALL GRASS

To its historic rivals, a weakened Iran might seem like a tantalizing prospect. For Israelis, it represents a signal achievement against their most tenacious and lethal adversary. For Prime Minister Benjamin Netanyahu, eroding the advantage that Tehran appeared to have gained in the aftermath of the October 7 attacks in 2023 vindicates his enduring obsession with the Iranian threat; together with the setbacks he has inflicted on Hezbollah and Hamas, this has allowed for a dramatic rehabilitation of his political standing at home. After years of debate and an increasing American reluctance to use military force in the Middle East, the willingness of the United States to join the campaign against Iran provided the Israelis with a welcome reassurance that Washington remains prepared to take risks to achieve strategic aims.

But the aftermath of the strikes presents new uncertainties for Israel. Unlike Trump, Israeli leaders are under no illusion that Iran’s nuclear program has been “obliterated”; they fully anticipate that Tehran will seek to reconstitute its capabilities and are prepared to continue the campaign to ensure that Iran cannot succeed. The relative ease with which Israel accomplished its objectives in June may lead it to embark on a semipermanent operation to “mow the grass,” aimed at continuously degrading its adversaries’ capabilities, as Israel has done over many years in Lebanon and Syria. Those campaigns continue to this day, and Israelis point to their success in contributing to the hobbling of Hezbollah and the demise of the Assad regime in Syria.

Still, the prospect of a long-lasting military campaign to degrade Iran’s nuclear capabilities will face significant obstacles, especially concerning any U.S. role. Trump has staked his political career on skepticism of sustained military engagements in the Middle East, and according to NBC News, he rejected a plan proposed by his own military commanders that could have ensured more lasting damage to Iran’s nuclear ambitions. Israelis recognize that their ability to follow up on their military success faces constraints, especially the high cost and limited supply of interceptors for the country’s missile defenses, which are necessary to protect Israel from Iranian assaults. This shortage informed Washington’s calculus in demanding a cease-fire after a mere 12 days.

Munitions and budgets are not simply issues for Israel; the high demand for interceptor missiles and for U.S. military assets that were shifted to the region to help defend the Jewish state are straining essential resources Washington needs in other areas, especially Asia. Prolonging the Israel-Iran conflict would come at the expense of the Trump administration’s determination to focus on defending U.S. interests in the Indo-Pacific in the face of an increasingly assertive Chinese military.

Tehran’s neighbors, meanwhile, look at ongoing military action against Iran and see intolerable risks of instability and escalation. Determined to continue transforming their economies and societies into global hubs of technology, tourism, and trade, the Saudis and other Gulf leaders have sought in recent years to co-opt rather than confront Tehran, calculating that excluding it from the regional order would only invite further Iranian malfeasance.

The Israeli and American strikes on Iran’s nuclear program have bolstered this inclination. The Gulf states derive little sense of security from having a wounded colossus on their periphery. Leaders in those countries remember the havoc wreaked by an incipient Islamic Republic that sought to shore up its revolutionary enterprise through acts of terror. They also remember the shadow cast by a defeated but defiant Saddam Hussein over many decades.

Tehran’s closing act during the recent war—a barrage of ballistic missiles targeting the U.S. airbase in Qatar—was mostly for show. The Iranians forewarned both the Qataris and the Americans, and the attack did little damage to the hastily emptied facility. But it nevertheless reinforced the danger that an isolated and embittered Iran could pose to its neighbors. As Anwar Gargash, a diplomatic adviser to the president of the United Arab Emirates, remarked in a conversation published by GEG, a French think tank, “We have seen in many instances that when a nation feels attacked, nationalism rises. We cannot preclude that scenario.” He added, “You cannot reshape the region through belligerent force. You might resolve some issues, but it will create counter issues. We have to look at the history of the Middle East and the lessons of the past 20 years. Using military force is not an instant solution.”

Despite close security cooperation between Israel and the Gulf states, the prospect of an Israeli-dominated order hardly seems conducive to the latter’s aspirations. Israel’s embrace of aggressive preemption across the region promises more disruptions for the ambitious economic plans of Gulf leaders. Netanyahu’s continuation of the war in Gaza, even in the absence of any discernible military objectives, has also impeded the expansion of the Abraham Accords, the U.S.-brokered deals that saw some Arab states normalize their relations with Israel.

Some U.S. officials have come to share this sense of uneasiness about Israel’s strategy. Their concerns were heightened by Israel’s attack on Syria in July, when it struck a Defense Ministry building and a site near the presidential palace. After the Assad regime collapsed in late 2024, Washington and its regional allies embraced Syria’s new government, even though its leaders had previously aligned with al-Qaeda. The Gulf states and the Trump administration see Damascus as a potential anchor for a regional security order grounded in Arab sovereignty. For its part, Turkey is heavily invested, both strategically and economically, in the new government in Damascus, and views Israel’s actions in Syria as deliberately destabilizing. Intensified sectarian violence in Syria, together with Israeli efforts to undermine the new government, could stir a new and potentially even more dangerous rivalry between Israel and Turkey and provide Tehran an opening to revive its influence in Syria and its transnational network of proxy militias.

WORTH A SHOT

The erosion of Iranian power resolves a long-standing challenge but also opens up a new set of risks to regional stability. One thing is certain: Washington is unlikely to take full ownership of managing this precarious new balance of power in the Middle East. Trump has a long track record of critiquing his predecessors’ costly entanglements in the Middle East. He can now tout his successful intervention and rapid exit from the Iran conflict as expiating the sins of his predecessors. “He’s no Jimmy Carter,” an unnamed Trump administration official crowed to Axios after the U.S. strikes in June. In remarks at the White House, Trump himself invoked Carter’s 1980 hostage rescue operation that ended in disaster; he reveled in the comparison and celebrated the success of his airstrikes. “China, Russia, they were all watching,” Trump noted. “Everybody was watching. We have the greatest equipment anywhere in the world. We have the greatest people anywhere in the world, and we have the strongest military anywhere in the world.”

Despite the superlatives, the Iranian nuclear program has not been eliminated. Achieving that goal conclusively will require either diplomacy or regime change, and only the former is within reach. Trump has always insisted that he can negotiate a better deal than the 2015 Joint Comprehensive Plan of Action; based on his public commentary, he seems prepared to consider more normal diplomatic and economic relations with Tehran. Even if he were snubbed, the act of making such an offer could provide a powerful opportunity to highlight the divide between the aspirations of Iran’s current leadership and those of its citizens.

Devising a new diplomatic framework for managing the Iran nuclear crisis will not be easy. Iran’s foreign minister, Abbas Araghchi, has left the door open to talks while emphasizing that the strikes make the pathway to any agreement much more difficult. Iranian officials resent the fact that a previously scheduled round of negotiations was used to lull them into complacency in advance of Israel’s surprise attack, and some have signaled that confidence-building measures would be necessary to persuade Tehran to come back to the table.

Washington’s partners in Europe stepped up during the Biden administration and, in the face of American reluctance, advocated for the IAEA to censure Tehran for not cooperating with the agency’s inspections and refusing to answer questions about its nuclear work. European countries can play a useful role now, too, by triggering the so-called snapback clause of the Joint Comprehensive Plan of Action, to which they and Iran are still technically parties. The clause is one of the fail-safe mechanisms built into the 2015 nuclear deal; if activated by a party to the deal, it would reimpose a raft of UN economic sanctions on Iran. Still, Iran’s distrust of Western countries and the endurance of the regime under dire circumstances mean that even this tool will have limited efficacy in terms of constraining an intractable Iranian leadership.

Diplomacy is not a solution in and of itself, but a concerted effort to draw Tehran into a meaningful dialogue about the future of its nuclear program would buy time, widen inevitable divergences within the Iranian regime, and enhance transparency around the facilities and systems that would facilitate any Iranian nuclear breakout. A new regional order is beginning to emerge in which Iran and its proxies no longer occupy central stage. Although the June war was executed brilliantly, preventing an Iranian bomb requires more than a robust set of targets. And a revolutionary regime cannot be permanently subdued by force.

Iranian leaders have little reason to trust American inducements to dialogue, but Trump may be able to use his disdain for politics as usual to change the narrative. His willingness to intervene on behalf of the Israeli military operation in Iran gives him unique credibility and room to maneuver. Before the June war, U.S. and Iranian negotiators were discussing creative ideas for navigating the question of uranium enrichment, a central sticking point throughout the decades of contention and negotiation over Iran’s nuclear activities. Several of the reported proposals, such as a regional enrichment consortium outside Iranian territory as well as foreign investment in civilian nuclear energy facilities, could provide an off-ramp for this impasse, especially if paired with sanctions relief. Any deal would also need to place restrictions on Iran’s missile development and allow inspectors unfettered access to verify Iranian compliance.

Such provisions would prove difficult for Iranian officials to stomach, despite the toll of the war. To reinforce the credibility of any proposals, Trump should continue to highlight his desire to see a brighter future for Iran and a different relationship between the two countries. Even if it doesn’t succeed, an invitation by the United States for a new diplomatic and economic relationship with Tehran could sow the seeds of a strategic splintering of the regime at a time of crisis.

With Iranian power and influence waning, and with the challenges of an ascendant China and a recalcitrant Russia necessarily dominating the American national security agenda, indifference may appear to be the most appealing option for Washington. This would be a mistake. The world stands on the precipice of a dangerous era of nuclear proliferation that risks expanding the geography of catastrophic risk. It is essential to devise a diplomatic pathway that reimposes transparency on Iran’s nuclear enterprise and creates a way to escape the escalatory storm that lurks just below the surface of the uneasy postwar calm.