As negotiations between the United States and Iran begin in earnest over Iran’s nuclear program, history offers a clear warning: The greatest proliferation risks lie not in what states declare, but in what they conceal.

For four decades, the nuclear ambitions of Iran, Iraq, Libya, North Korea, and Syria have tested the international nonproliferation regime, which requires non-nuclear-weapon State Parties to conclude a safeguards agreement with the International Atomic Energy Agency (IAEA) allowing IAEA inspectors to verify that nuclear materials and facilities are not diverted from peaceful to military uses. In each case, formal adherence by these five states to the Nuclear Non-Proliferation Treaty (NPT) failed to prevent covert efforts to acquire nuclear weapons. North Korea ultimately crossed the nuclear threshold, underscoring the consequences of verification failure.

We have seen this pattern before. Proliferation persists not because evidence is absent, but because it is incomplete, obscured, or insufficiently exploited. Detecting and deterring these hidden pathways require more than traditional safeguards. At a minimum, it requires the comprehensive implementation of the IAEA’s Additional Protocol, which allows the IAEA expanded access to verify not only that declared facilities and materials are compliant, but to inspect potential undeclared activities.

Hidden Programs and Delayed Detection

In Iraq, United Nations inspectors uncovered a vast clandestine nuclear weapons program after the 1991 Gulf War despite Iraq’s status as a party to the NPT. A decade later, Syria pursued a similar approach. Its undeclared reactor at Al Kibar, capable of producing plutonium, remained undetected until it was destroyed in 2007. Only afterward did IAEA analysis confirm the presence of undeclared nuclear material.

These cases exposed a fundamental weakness: Traditional safeguards focused on declared materials are not enough. The safeguards formula was not designed to reliably uncover what states choose to conceal.

Rollback is Possible but Fragile

Libya demonstrates that while nuclear rollback is possible, it is not durable on its own.  Due to a combination of sanctions, diplomacy, and incentives, Libya agreed in 2003 to dismantle key elements of its nuclear program and opened its facilities to international inspection. Yet the collapse of the Gaddafi-led Libyan state in 2011 reinforced a different lesson: abandoning a nuclear program does not guarantee long-term security. That perception continues to shape incentives for proliferation far beyond Tripoli.

When Nonproliferation Fails

North Korea is what happens when nonproliferation unravels. In the 1990s, IAEA inspectors identified inconsistencies in Pyongyang’s declarations concerning plutonium production and the reprocessing of spent nuclear fuel. By 2002, inspectors were expelled; by 2003, North Korea withdrew from the NPT. It has since conducted multiple nuclear tests and possesses a rapidly expanding nuclear arsenal. Once access and verification ended, so too did the ability to prevent the emergence of a new nuclear weapons state.

Iran: A Threshold State with Material and Capability

Iran is a more difficult and urgent challenge. Unlike Libya or Syria, it has mastered key elements of the nuclear fuel cycle, including uranium enrichment and conversion. Although Iran halted aspects of its structured weapons program in 2003, its subsequent record includes undeclared activities and incomplete disclosures.

The 2015 Joint Comprehensive Plan of Action (JCPOA) imposed limits on enrichment and stockpiles and expanded the scope of the IAEA’s monitoring. Those constraints on Iran’s program eroded after the U.S. withdrew from the agreement in 2018. Iran has since produced significant quantities of uranium enriched up to 60 % and reduced cooperation with IAEA inspectors.

Military strikes in 2025 and 2026 damaged infrastructure but did not eliminate Iran’s capabilities. More importantly, they introduced new uncertainty regarding the location and status of enriched material. Iran retains both the technical knowledge and the material base to reconstitute its program.

Lessons for a Viable Nuclear Agreement with Iran

First, covert pathways pose the greatest risk. The most consequential proliferation activities occur outside declared channels.

Second, transparency must extend beyond declared materials. Verification must be capable of detecting undeclared facilities, activities, and supply chains.

Third, military action may set back a nuclear program, but it cannot erase it. Scientific knowledge endures, and the prospect of conflict can accelerate a decision to pursue nuclear weapons.

Fourth, while diplomacy often favors headlines, the commitment of these states to the pursuit of nuclear weapons has lasted for decades. A verification regime must be sustained and enforced over the long haul to eliminate the threat.

Finally, once a state acquires nuclear weapons, reversal is extraordinarily difficult.

Why the Additional Protocol is Essential

These lessons point to a single conclusion: intrusive, sustained verification is indispensable. The Additional Protocol provides the most effective mechanism currently available. It expands declarations across the nuclear fuel cycle, enables short-notice inspections, and allows environmental sampling at undeclared sites. Because Iran’s program has grown in size and complexity since the collapse of the JCPOA; any new agreement must go further than previous arrangements.

Iran signed but never ratified the Additional Protocol and has only implemented it provisionally. Any future agreement that limits enrichment but fails to ensure legally binding, fully implemented Additional Protocol measures will leave critical gaps in verification.

Conclusion: No Additional Protocol, No Deal

Iran’s nuclear knowledge will not disappear. The objective is not complete denuclearization, but rather to ensure that any move toward weaponization is detected early enough to allow an effective response. The stakes could not be higher. A nuclear-armed Iran would almost certainly unleash a cascade of nuclear weapons programs across the region.

The next plan requires continuous, intrusive verification of both declared and undeclared activities, supported by a credible enforcement framework involving the United States, European partners, regional states, and the United Nations. Limits on enrichment alone are insufficient. If robust verification is missing, Iran will retain a latent weapons option. The regime’s survival through recent conflict may also shape its threat perceptions, potentially reinforcing the perceived value of retaining a nuclear option.

The record of Iran, Iraq, Syria, Libya, and North Korea is unambiguous: Without intrusive verification, nonproliferation cannot be assured. Without the Additional Protocol as a foundation for nuclear transparency in Iran, there is no confidence. And without confidence, there should be no deal.