Volume 17, Issue 3
June 12, 2025
With Iran on the threshold of nuclear weapons, effective diplomacy is the only viable option for sustainably reducing Iran’s proliferation risk. President Donald Trump, to his credit, is seeking a new nuclear deal with Iran. The current U.S. strategy, however, risks derailing negotiations and pushing the two countries closer to a conflict, an outcome Trump wants to avoid. Unless Trump and his negotiating team are willing to show more flexibility and realism regarding the future of Iran’s nuclear activities, the United States will miss another opportunity to address the growing proliferation risk posed by Iran’s expanding program and the risk of conflict will increase.
After five rounds of negotiations and an exchange of proposals, uranium enrichment is a key point of contention that could spoil the prospects for diplomacy. Initial comments from Steve Witkoff, U.S. Special Envoy for the Middle East and lead negotiator, suggested Iran could retain a limited uranium enrichment program under strict monitoring. Reports on a written proposal the United States shared with Iran in June also indicate some flexibility on the question of enrichment: Iran would retain limited domestic enrichment that would phase out with the creation of a regional enrichment consortium. Trump’s recent public rhetoric, however, presents a more maximalist approach to a deal: complete elimination of the enrichment program.
Lawmakers in Congress from both parties and Israeli officials, including Prime Minister Benjamin Netanyahu, appear to be pushing Trump toward this more extreme demand of zero enrichment, a goal which is unnecessary for an effective nonproliferation agreement and untenable for Iran. If proponents of the zero enrichment approach succeed in setting dismantlement as the U.S. bottom line for an agreement, it will kill the prospects for a deal that reduces Iran’s proliferation risk.
If Trump is serious about reaching an effective deal, he needs to abandon zero enrichment as a requirement, both at the negotiating table and publicly, and consistently message more pragmatic U.S. objectives for an agreement. With the right combination of limits and monitoring, the United States and Iran can negotiate a strong, effective nonproliferation agreement that includes a tightly circumscribed uranium enrichment program in line with Tehran’s legitimate, but limited, needs for a civil nuclear program.
A Right to Enrich?
The issue of enrichment is particularly contentious because the same technology that can be used to produce reactor fuel for a civil program can be calibrated to produce fissile material for weapons. Furthermore, states dispute whether technologies used to produce fissile material, such as enrichment, are included in the Nuclear Nonproliferation Treaty (NPT) provisions that recognize the rights of non-nuclear weapon states to peaceful nuclear programs.
The NPT declares it is the “inalienable right” of all states to develop nuclear programs for peaceful purposes under IAEA safeguards. According to Article IV, all parties “have the right to participate in, the fullest possible exchange of equipment, materials and scientific and technological information for the peaceful uses of nuclear energy.” The NPT does not, however, specify if uranium enrichment and plutonium reprocessing, the two technologies used to produce fissile materials used in nuclear weapons, are included within the rights specified under Article IV.
Iran, like other NPT members, interprets Article IV as inclusive of uranium enrichment and maintains that it will not give up its right to enrich under any nuclear agreement. President Massoud Pezeshkian reiterated Iran’s position in a June 3 speech, saying Iran “will not compromise on our nuclear rights by any means.”
Any "right" to enrich uranium as a non-nuclear weapon state under the NPT also comes with responsibilities to comply with safeguards designed to prevent diversion for military purposes. Although Iran’s uranium enrichment is currently under safeguards, its initial uranium enrichment activities were conducted in violation of its NPT safeguards obligations as part of an organized pre-2003 nuclear weapons effort.
When Iran refused to cooperate with an International Atomic Energy Agency (IAEA) investigation into its undeclared nuclear activities, the agency’s Board of Governors reported Iran to the Security Council for noncompliance with its safeguards agreement in 2006. The Security Council then passed a series of resolutions requiring Iran to cooperate with the agency and suspend certain nuclear activities, including its uranium enrichment program. The requirement for suspension was intended to push Iran to negotiate over its nuclear program and was superseded in 2015, when the Security Council unanimously adopted Resolution 2231, which endorsed the nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA).
The United States, in contrast, asserts that the NPT’s Article IV does not include the “right to enrich” and has sought to prevent the spread of uranium enrichment and reprocessing technologies as part of its nonproliferation policy. Both Presidents George W. Bush and Barack Obama, however, came to recognize that this was not a feasible approach to the risk posed by Iran.
When the IAEA raised concerns about illicit Iranian nuclear activities during the George W. Bush administration and negotiations with Iran commenced, the United States initially pushed for a deal with Iran that would prohibit uranium enrichment and plutonium reprocessing. Some of the officials around Bush advocating these maximalist demands appeared intent on disrupting the European-led diplomacy with Iran and advancing a military option or regime change strategy, rather than exercising flexibility to reach a deal.
The demand for zero enrichment, for instance, appears to have contributed to the U.S. rejection of an Iranian proposal in 2005 that included capping the uranium enrichment program 164 centrifuges, or one cascade (as of May 2025, Iran has 125 installed cascades, about two-thirds of which are advanced machines that enrich uranium more efficiently.)
By 2006, the Bush administration’s approach shifted. U.S. officials suggested that, after a moratorium during which Iran worked with the IAEA to address the agency’s questions, enrichment could resume if Iran demonstrated a “credible and coherent economic rationale in support of the existing civilian power generation program.” This formulation was consistent with Security Council demands that Iran suspend enrichment but angered more hawkish members of the Bush administration.
After leaving the Bush administration, John Bolton criticized the U.S. diplomatic approach and dismissed it as a viable option for addressing Iran’s proliferation risk. He said in a 2007 interview that, on Iran, the “the choice is between the use of force and Iran with nuclear weapons.”
Although the conditions outlined by the Bush administration likely would have taken Iran years to meet, it did mark a shift in U.S. thinking that Obama continued after taking office in 2009. Obama initially pushed for Iran to suspend its uranium enrichment program, as required by UN Security Council resolutions, before commencing negotiations. As Secretary of State Hillary Clinton testified to the House Foreign Affairs Committee in 2011, “it has been our position that under very strict conditions Iran would, sometime in the future, having responded to the international community's concerns and irreversibly shut down its nuclear weapons program, have such a right [to enrich and reprocess domestically] under IAEA inspections.”
By 2012 the United States dropped the demand for suspension as a condition for negotiations and Obama’s acknowledgement that Iran could retain enrichment in a deal played a critical role in advancing negotiations that eventually produced the Joint Comprehensive Plan of Action (JCPOA) in 2015.
The Trump administration’s current approach is reminiscent of the Bush-era’s initial Iran policy that failed to constrain Tehran’s program. Similar to the Bush administration, Trump advisors are pushing the United States toward maximalist, unnecessary objectives for a nonproliferation agreement that appear designed to disrupt the negotiating process, rather than support Trump’s desire to negotiate an agreement that can effectively block Iran’s pathways to nuclear weapons.
After Witkoff suggested Iran may retain limited enrichment under strict monitoring at the onset of negotiations, he faced a swift backlash, including from key Trump advisors, such as Secretary of State Marco Rubio. In advocating for zero enrichment, Rubio tried to argue that Iran is the only non-nuclear weapon state that enriches uranium. Rubio, however, is incorrect. Japan and Brazil both enrich uranium as part of their civil nuclear programs. The Urenco fuel consortium operates enrichment facilities in Germany and the Netherlands. Both Brazil and West Germany were states of proliferation concern in the past. These cases demonstrate that even states with a historic interest in nuclear weapons development can operate these technologies under the appropriate safeguards and international scrutiny.
Iran’s Enrichment Redline
Iran has poured significant resources into developing its uranium enrichment program and views it as both necessary for its civil nuclear ambitions and a source of leverage. Although Iran’s Supreme Leader Ayatollah Ali Khamenei has given Pezeshkian latitude to pursue negotiations with the United States, Khamenei has made clear that zero enrichment, or any arrangement that requires Iran to depend solely on foreign entities for uranium fuel (such as a regional consortium), are redlines.
There appear to be several factors motivating Iran’s position on retaining enrichment. First, Iran seeks to be treated as a normal non-nuclear weapon state under the NPT. Given that Tehran views enrichment as a right conferred by the treaty, it does not want to negotiate away what it perceives as a right or to be singled out for restrictions that other states do not face.
Second, Iran takes great pride in its civil nuclear program and has ambitious plans for expanding nuclear activities in areas such as energy generation and medical isotope production. Iran anticipates needs for domestically produced uranium fuel for its planned reactors. As the head of the Atomic Energy Organization of Iran Mohammad Eslami described, Iran sees “enrichment as the foundation and pillar of the country's nuclear industry.”
Currently, Iran’s actual needs for enriched uranium are small and covered by foreign suppliers. Iran imports 20 percent enriched fuel for its Tehran Research Reactor, which produces medical isotopes, and has a contract with Russia’s state-run nuclear company, Rosatom, for fueling its operating power unit at Bushehr. According to a memorandum between Rosatom and the Atomic Energy Organization of Iran, Rosatom will also supply the other reactor units that it is constructing at that site.
Although the reimposition of U.S. and European sanctions on Iran has not hindered the country’s ability to procure the necessary fuel for its operating reactors, Iran does have some legitimate reason to distrust international suppliers as a source for providing enriched uranium fuel and to be concerned about the future impact of sanctions on fuel supplies. In the 1970s, when the Shah of Iran outlined an ambitious nuclear energy plan, he invested in a European enrichment consortium, Eurodif, that was based in France. Despite making a $1 billion investment in the construction of the Eurodif facility that would have entitled Iran to ten percent of the fuel produced, Iran never received any enriched uranium. Iran only recouped its investment after a prolonged legal battle. Iran points to the Eurodif experience as evidence that it cannot rely on international suppliers for reactor fuel. Furthermore, Russia’s illegal invasion of Ukraine and related politicization of energy supplies likely drive further concerns about the reliance of third parties for importing uranium fuel.
Even though Iran’s current needs for enriched uranium are being met, Tehran envisions domestically fueling planned reactors, including an unfinished research reactor, the Arak Reactor or IR-40, and a domestically designed power reactor at Darkhovin. In a June 4 speech, Khamenei, emphasized Iran’s desire to be self-sufficient in fueling its reactors. He said the U.S. approach to negotiations “contradicts our nation’s belief in self-reliance” and said that uranium enrichment is key to Iran’s energy independence.
Third, Iran appears to view uranium enrichment as a guarantee that it can rebuild leverage against the United States should Washington withdraw from a future nuclear deal. The JCPOA experience demonstrated how quickly and effectively the United States can reimpose sanctions and ramp up economic pressure on Iran, even with the opposition of the international community. If the United States were to withdraw from a new nuclear deal, after Iran had given up its uranium enrichment program, it would take a lot longer for Tehran to restore those capabilities. But by retaining a uranium enrichment capability, Iran views itself on more equal footing with the United States. It is unrealistic to demand that Iran completely give up what it views as a guarantee for sustaining an agreement while the United States retains effective tools of pressure.
None of Iran’s arguments for uranium enrichment should override legitimate nonproliferation objectives and the necessity of rolling back the country’s current nuclear activities. Given Iran’s pre-2003 nuclear weapons program and active debate in Tehran about the security value of nuclear weapons, Iran’s uranium enrichment program poses a serious proliferation threat and must be rolled back. The current enrichment program, for instance, includes activities such as enrichment to 60 percent that have no civil justification and puts Iran in a better position to quickly produce enough weapons-grade material for a bomb.
But demanding zero enrichment is not necessary to address Iran’s proliferation risk. It is possible to negotiate an agreement with a tightly circumscribed uranium enrichment program that meets U.S. nonproliferation objectives and Iran’s practical needs for enriched uranium. Iranian officials, including Foreign Minister and lead negotiator Abbas Araghchi, have stated Iran is willing to reduce its level of enrichment and address the stockpiles of highly-enriched uranium in the country, but will not give up enrichment entirely. In short, by holding out for zero enrichment, the United States is jeopardizing the opportunity to negotiate an effective, nonproliferation deal.
Enrichment Limits are Necessary, Prohibition is Not
Trump has stated consistently that the U.S. goal for a deal is to prevent a nuclear-armed Iran. The best way to do that is through a pragmatic agreement that combines nuclear limits with intrusive monitoring—conditions Iran says it will accept, so long as its nuclear rights are respected.
Given that that Iran’s proliferation risk cannot be completely eliminated due to the irreversibility of the knowledge Iran has gained about enrichment and weapons development, the United States needs to determine what level of risk it can tolerate. Iran’s current position—perched on the threshold of nuclear weapons—is unsustainable and zero enrichment is impractical and unnecessary. The solution lies between these extremes.
Currently, Iran is enriching uranium to 60 percent at both is large-scale uranium enrichment facility at Natanz and its smaller, underground Fordow facility. Iran has amassed enough material enriched to that level and installed enough centrifuges that has a near-zero breakout (the time necessary to produce enough fissile material for a bomb, or 25 kilograms of uranium enriched to 90 percent). As of late May 2025, Iran could produce enough weapons-grade uranium for one bomb within days, and within weeks, enough for about 8-10 warheads.
The IAEA would quickly detect any move by Iran to increase enrichment to weapons-grade levels at its declared sites. But with breakout so short, the international community may not have enough time to respond before Iran could divert the weapons-grade uranium to covert locations and begin the weaponization process.
There is also a real risk that, in the event of an imminent military strike or a decision is made to weaponize, Iran diverts 60 percent material to a covert site and stores it or enriches it to weapons-grade levels. Iran’s development of more efficient centrifuges would allow Tehran to enrich to weapons grade using few machines at an undeclared facility with a smaller footprint. Although U.S. intelligence has proven adept and detecting illicit Iranian nuclear facilities in the past, there is a risk that Tehran could enrich to weapons-grade levels before a new facility could be detected, particularly if Iran has already diverted centrifuges to that site.
To reduce the threat posed by Iran’s current enrichment program, the Trump administration should focus its on two priorities: lengthening breakout and, most critically, increasing international monitoring to ensure rapid detection of any diversion of nuclear materials from the declared program or deviations from the limits set by a deal.
On the first priority, extending breakout, an effective deal should seek to increase the breakout time to a long enough period that the international community can detect and respond to any move by Iran to develop a bomb. The right combination of limits on enrichment capacity, enrichment level, and stockpiles could extend breakout from days to months. Building breakout back up to 3-4 months, for example, would provide an opportunity to engage Iran before immediately resorting to force to disrupt any weaponization efforts. A longer breakout, combined with rapid detection of any deviation from declared enrichment activities, would maximize the time available to prevent a nuclear-armed Iran.
There is no single pathway to extending breakout. The United States and Iran can consider different combinations of limits that address Iran’s practical needs, while providing bulwark against proliferation.
One option would be to roll back Iran’s uranium enrichment level back to less than 5 percent, which is a level suitable for Iran’s operating and planned power reactors. Iran currently has no practical need for uranium enriched to 60 percent and no real need for uranium enriched to 20 percent (Iran continues to purchase 20 percent fuel for medical isotope production at Tehran Research Reactor from Russia.) The agreement could limit Iran’s to the less than 5 percent level in perpetuity, with a clause allowing the United States and Iran to revisit the enrichment level and increase it to 20 percent down in the road if Iran demonstrates a practical need for the Tehran Research Reactor or runs out of fuel for it (or is unable to purchase it). Any Iranian plans for new reactors requiring 20 percent enriched uranium could be reviewed by the United States and Iran and enrichment scaled up if, and when, it would be necessary for those units.
In addition to setting an enrichment limit of five percent, Iran should be required to downblend its 60 percent enriched uranium to 20 percent. Iran could be permitted to retain the 20 percent stockpile and attempt to sell the material on the open market (to a state with safeguards) within a set period of time. If Iran does not sell the material, it could retain an agreed-upon amount of 20 percent material fuel the TRR for a set period and downblend the rest to less than five percent or natural levels.
To effectively increase Iran’s breakout time, the enrichment limit and stockpile caps should be combined with an agreed-upon enrichment capacity. Iran’s current enrichment program, which includes first-generation IR1 centrifuges as well as more efficient IR2, IR4, and IR6 machines, is much larger than what is necessary for the country’s current fuel supply needs. One option to reduce capacity that might be more appealing to Iran would be to let Tehran determine what mix of centrifuges it uses in its limited program. Under the JPCOA, Iran was limited to 5,060 IR-1s. But Tehran is unlikely to want to rely on that model going forward, given its advances in producing and operating the more efficient IR2, IR4, and IR6 machines. Iran and the United States could agree upon a certain enrichment capacity and, with the verification of the IAEA, allow Iran to determine what mix of centrifuges it uses to achieve that goal. Excess machines could be dismantled and stored. Furthermore, a deal could prohibit certain cascade configurations, such as using modified subleaders, a process that allows Iran to switch between enrichment levels more quickly.
Given Iran’s plans to expand its program, the Washington and Tehran could agree to revisit enrichment capacity and stockpile limits if Iran hit certain milestones in developing new reactors and needed additional reactor fuel. The IAEA could verify when, and if, Iran’s reactor construction met certain milestones to trigger increases.
Second, and most importantly, an agreement should include intrusive monitoring, particularly as it relates to Iran’s uranium fuel cycle activities. More intrusive monitoring will provide greater assurance that the IAEA will rapidly detect any deviation from agreed upon limits and restore confidence that Iran did not conduct undeclared nuclear activities during the period of reduced IAEA access. A strong verification regime will also help deter Iran from diverting materials to a covert program.
More specifically, a deal could require Iran to implement, and ideally ratify, of the additional protocol to its safeguards agreement. That would give IAEA inspectors expanded access to key information and sites and more tools for investigating evidence of undeclared activities. Ratification would provide greater assurance of Iran’s intentions to abide by this more stringent safeguards agreement in perpetuity. Additionally, the deal could require Iran to allow online enrichment monitoring, giving the IAEA the ability to monitor enrichment levels in real time, and daily access to Iran’s enrichment facilities. Consolidating enrichment at Natanz would also reduce risk.
The deal could also include, or reference, an understanding between Iran and IAEA on restoring the agency’s knowledge about Iran’s nuclear program. That understanding should have agreed upon actions and clear deadlines for Tehran to provide the IAEA with information about work relevant to Iran’s nuclear program that was conducted when the agency had less access to information and sites. It would include assisting the agency in accounting for centrifuge production and uranium ore concentrate stocks. Timely provision of this information would assist the IAEA in rebuilding a history of Iran’s nuclear activities and reestablishing baselines against which limits in a deal could be verified.
Ensuring that Iran fully cooperates with the agency’s efforts in this regard will be critical for ensuring key limits in a future, such as centrifuge stockpiles, can be verified, and to provide greater assurance that Iran did not conduct covert nuclear activities after breaching its JCPOA obligations. Failure to do risks the sustainability of a deal and could drive speculation that Iran is cheating on the limits of a future deal.
The right combination of limits could increase Iran’s breakout time from days to months, significantly reducing the immediacy of the proliferation risk. This, combined with intrusive IAEA monitoring, would provide greater assurance that any move away from the agreed-upon limits would be quickly detected, maximizing the amount of time the international community would have to respond if Iran did make the decision to develop nuclear weapons or deviate from its declared nuclear program.
Bottom Lines
Holding out for Iran to dismantle its uranium enrichment program does not solve the nuclear crisis—it is more likely to exacerbate the current challenge by pushing Iran away the negotiating table. Trump cannot afford to waste this opportunity by making the perceived perfect (zero enrichment and dismantlement of Iran's nuclear infrastructure) the enemy of the good (limited enrichment for a longer, if not indefinite period).
If the United States and Iran can reach a win-win agreement on uranium enrichment and monitoring of that program, it is likely that the two sides can come to an agreement on other issues that will need to be covered in an effective nonproliferation deal, such as preventing plutonium reprocessing, prohibition of certain weaponization activities, and the monitoring and verification in those areas.
An effective, verifiable deal is within Trump’s grasp if he sees the pressure to pursue zero enrichment for what it really is—a cynical ploy to kill negotiations—and focuses on pragmatic, realistic, and achievable objectives that accomplish U.S. nonproliferation goals.—KELSEY DAVENPORT, Nonproliferation Policy Director