With Khamenei dead, Crown Prince Pahlavi could be Iran’s next leader. What would it mean for nuclear security?

Ayatollah Ali Khamenei, Iran’s supreme leader, is dead.

On Saturday, the United States and Israeli armed forces reportedly decimated the Islamic Republic of Iran’s military and security apparatus, as well as killed many high-ranking officers of the Islamic Revolutionary Guard Corps, or IRGC, making it unclear who could emerge domestically as a successor.

By Sunday, the regime formed a three-person interim council tasked with naming a successor, with Ayatollah Alireza Arafi acting as the interim supreme leader.

Khamenei’s death sends a clear message to whoever could replace him: Capitulate to the Trump administration’s demands, or face the same fate in a future strike. But such a leader seems unlikely to be named for a few reasons.

The first is that all the members of the interim council—which includes Arafi, as well as Iran’s President Masoud Pezeshkian and the Supreme Court Chief Justice Gholam-Hossein Mohseni-Ejei—are themselves regime insiders who could only have risen to their posts after ideological vetting by Khamenei himself. That makes the possibility of a true reformer emerging from this council essentially nonexistent. More likely, the next leader will be chosen among IRGC hardliners and those sympathetic to them. The IRGC is the strongest security faction in Iran, and its survival is intimately linked to the regime’s survival.

This candidate will likely adopt one of two postures. The first, and probably less likely, is a to-the-death strongman: With the regime’s very survival now in jeopardy, a less restrained new leader may completely abandon the nuclear ambiguity and incrementalism of Khamenei’s rule in favor of a last-ditch rush to develop a nuclear weapon for some modicum of deterrence. Iran could either assemble one or a few simple nuclear weapons within weeks from the stockpile of 60-percent enriched uranium (if it survived the June and this weekend’s US strikes), or divert some of this material to proxy groups who could assemble a crude gun-type weapon.

The regime has already suffered tremendous losses of materiel and senior officers since June 2025, and domestic opposition is at an all-time high. Such an inflammatory stance is unlikely to end the war, stabilize the country, or establish a new leader as an enduring head of state. The second, more likely stance, is one of performative reform. Such a candidate might signal to the West a willingness to negotiate and maybe even offer some modest concessions regarding its nuclear program—Washington’s most pressing issue. But, once more, this may largely be a stalling tactic used to consolidate power domestically and crush protests before returning to the status quo.

An arms control strategy that treats the Islamic Republic of Iran, or any element within it, as a normal negotiating partner capable of sustaining verifiable commitments must contend with a hard truth: The Iranian regime is a bad-faith actor. A government capable of killing thousands of its own civilians to remain in power will also lie, obstruct inspections, and weaponize ambiguity when it serves its survival.

However, as dangerous as the current power vacuum is, it may also be the greatest opportunity for transformative change in Iran.

Regime change has long been a talking point in Washington, but it lacked a sound alternative to make it actionable. For months now, hundreds of thousands of protestors in Iran and across the world have called on one specific opposition leader to lead: Crown Prince Reza Pahlavi, the son of the late Shah of Iran deposed during the 1979 Islamic Revolution.

On Sunday, Pahlavi told Fox News that the US strikes marked “the beginning of the very end of the regime,” saying it was time for Iranians to take back their country. If the regime’s grip continues to slip, Pahlavi—whose name has repeatedly become the opposition movement’s rallying point, both inside Iran and across the Iranian diaspora—is the most likely person to fill the void.

And as far as Iran’s nuclear program is concerned, Pahlavi has a plan.

Pahlavi’s transition plan. In April 2025, Pahlavi launched the Iran Prosperity Project, which includes a document analogous to a presidential candidate’s platform: the Emergency Phase Booklet. The document is part of Pahlavi’s transition plan, which draws from his circle of expert advisors and political supporters.

While observers should debate its politics and scrutinize its assumptions, from a safeguards perspective, Pahlavi’s plan contains something the Islamic Republic regime has repeatedly obstructed: international verification and transparency.

The booklet’s commitments are presented as specific actions in the first 100 days after the fall of the Islamic Republic (p. 53): In the first week, the transitional authorities would submit a formal letter declaring readiness for “unrestricted inspections of all nuclear sites,” committing to “full transparency and cooperation” with the International Atomic Energy Agency (IAEA). Then, in the first month, inspectors would be welcomed “to begin on-site evaluations,” and the transitional government would develop a “technical roadmap” to resolve “all outstanding nuclear issues” while simultaneously committing to the IAEA Additional Protocol and full compliance with the Nuclear Non-Proliferation Treaty. Finally, in the first 60 to 100 days, the transitional government would facilitate publication of a preliminary IAEA report and explicitly frame cooperation as the basis for lifting nuclear-related sanctions on Iran.

Critically, the booklet goes beyond inspections. In the energy section, the document calls for a specialized task force under transitional government oversight to evaluate the future of nuclear energy. It then lists several measures that ought to please arms control experts (p. 102-103): coordinating full inspections and monitoring at the key facilities of Natanz, Fordow, and Isfahan;

reassessing “the operational safety and strategic value” of the Bushehr Nuclear Power Plant; suspending “all nuclear activities indefinitely” pending review and international consultation; securing and safeguarding nuclear materials under international supervision to prevent leakage, theft, or misuse during the transition; and conducting environmental contamination testing near enrichment and suspected storage sites.

Taken together, these measures outline a posture designed to produce early, verifiable confidence and to do so promptly to mitigate risks of diversion and sabotage.

What the arms control community should do. Since the Munich Security Conference in February, many politicians and heads of state started meeting with Pahlavi. The international arms control community will need a seat at the table should Pahlavi return to Iran to lead a transitional government.

If the booklet is the offer, then arms control experts and the IAEA have leverage to shape the acceptance by making a public, conditional commitment now: If a transitional government implements unrestricted IAEA access, Additional Protocol compliance, and material security measures as described, the IAEA should advocate rapid technical engagement and phased sanctions relief tied to verified milestones.

In addition, the IAEA should begin necessary preparations for a safeguards implementation plan in cooperation with the transitional government, as the booklet explicitly anticipates immediate inspections and monitoring. Inspectors, equipment, and rapid environmental sampling capacity are required to achieve stability in the first 30 to 90 days.

Moral and technical convergence. No remaining element from within the Islamic Republic regime, reformist or otherwise, is a trustworthy choice for post-war normalization of international relations with Iran. Nor can any genuine opposition candidate be expected to emerge from within the regime.

Arms control professionals do not need to become activists or align themselves with a charismatic leader, but they need to be pragmatic. Pragmatism, here, is recognizing the value that Pahlavi provides as a stabilizing force and his much higher likelihood of engaging in good faith with the international community.

When the fog of war clears, the Pahlavi’s Emergency Phase Booklet can serve as an invitation to help Iranians build a post-regime nuclear file that is transparent and supervised, starting immediately, and starting with the IAEA.

The IAEA, meanwhile, should actively and technically support a transition that plausibly delivers what decades of engagement with the Islamic Republic have not: A verifiably peaceful Iranian nuclear program under full international scrutiny, with nuclear materials secured during the most dangerous window of all.

Regime change has now evolved from being a talking point to a current event. The arms control community must be prepared to seize the opportunity of a major nonproliferation breakthrough.