Could Iran Really Make A Nuclear Weapon?

Whether Iran has actively sought a nuclear weapon remains unanswered, but there is no doubt it pushed the limits of its enrichment program too far, and not by a little.

Information that proves this comes from several sources, most importantly the International Atomic Energy Agency, watchdog for the Nuclear Non-Proliferation Treaty. The IAEA is the only external body with the authority to conduct actual on-site inspections of Iran’s nuclear facilities while it remains a member of the NPT. Agency teams continued such visits as recently as one week before Israeli attacks began.

Experts consider it a point of key importance that the Iranian regime, despite decades of evasion and deception regarding IAEA requests for information, hasn’t withdrawn from the NPT. The only country to have ever done so is North Korea, which ended its membership in 2003 and conducted its first nuclear test three years later.

Uranium Enrichment Levels And What They Mean

Uranium enrichment involves increasing the percentage of uranium-235, the fissile isotope able to create a nuclear chain reaction. U-235 comprises only a very minor portion, 0.7%, of natural uranium, with the rest being U-238. Because these two isotopes have nearly identical chemical behavior, they have to be separated mechanically.

This is done by first converting uranium into a gas (uranium hexafluoride, UF₆), then feeding it into rapidly spinning centrifuges that force the heavier U-238 toward the outside, leaving U-235 nearer the center. Because the difference in weight is extremely small, the process isn’t quick. Depending on centrifuge technology, it can take six months to a year to achieve 5% enrichment, typical for low-enriched fuel in nuclear power reactors.

Several more months are needed to reach 20%, the lower threshold to highly enriched uranium. This is often used by research reactors that produce medical isotopes and industrial materials. A few such reactors for highly specialized uses can utilize 60%, which requires an additional month to achieve.

At this point, mere weeks or even days are needed to reach 90%, the lower limit of weapons grade. The 90% figure is no magic number but more a metric of high explosive probability and efficiency.

To understand this, it helps to know that the Hiroshima weapon had an enrichment level as low as 80%, with only 1.4% of the fuel having detonated. Admittedly, it would seem absurd to call this bomb, which destroyed 90% of the city and killed many tens of thousands of people, “inefficient.” But at today’s enrichment levels (93%-95%), the weapon would have been immensely more destructive.

The Threat of Iran’s Enrichment Capability

Latest data from the IAEA leaves little doubt about the potential threat Iran represents. This has built up especially since the first Trump Administration withdrew in 2018 from the Iran nuclear deal, known as the Joint Comprehensive Plan of Action, signed under President Barack Obama in 2015. With U.S. departure from the deal, the Iranians began to cut back on cooperating with IAEA inspectors.

In 2021, Iran revealed its plan for taking enrichment from 20% to 60%, and soon afterward ceased to provide any further details on its fuel-making program. In early 2023, the IAEA discovered particles enriched to as high as 83.7% at its Fordow Plant, built inside a mountain some 300 ft underground and recently targeted by U.S. bombers.

Then, in late 2024, inspectors concluded the Iranians had begun rapidly increasing its stockpile of 60% uranium. Though none of Iran’s research reactors can use 60%, the IAEA estimated that more than 400 kg had been produced by May 2025, a strikingly large amount.

The most logical conclusion was also the most unwelcome. As expressed in an analysis by the non-partisan Institute for Science and International Security, there could be no civilian use for so much material, not even as bargaining leverage in negotiations. “One has to conclude,” the ISIS states, that the intention of the Iranians “is to be prepared to produce large quantities of WGU [weapons grade uranium] as quickly as possible.”

How Quickly Could Iran Have Conceivably Made A Bomb?

Experts at ISIS believe Iran could convert its 60% stock into roughly 230 kg of weapons grade fuel in as little as 3 weeks. This would be enough for 9 nuclear weapons and would take place at Fordow.

A more sobering figure is that 25 kg, sufficient for a single weapon, could be produced in as little as 2-3 days, were operations not halted by wartime attacks. Whether this may have been done is unknown. Satellite imagery strongly suggests the 60% material was removed from Fordow before or shortly after Israeli attacks began.

Fuel alone, however, does not make a weapon. Have the Iranians pursued actual weapon design, even acquiring materials for a physical bomb? Intelligence reports have suggested this was indeed a goal in the early 2000s but likely ended in 2003. That was when the IAEA uncovered clear evidence of a clandestine nuclear program that flatly violated its obligations under the NPT.

Whether Tehran has since tried to restart the effort to physically assemble a nuclear device remains a source of debate. The IAEA appears to believe this is not the case. At the same time, they suggest that the stock of 60% enriched uranium has been disseminated to a number of sites for protection.

It is obvious that Iran has taken its enrichment levels far beyond any conceivable peaceful use, including as leverage in any future nuclear negotiation. Whether its capabilities have been greatly reduced by U.S. and Israeli attacks, they are not likely to have been destroyed. It has the know-how to rebuild advanced centrifuges and has almost certainly preserved significant portions of its most highly enriched fuel. The saga of uncertainty about Iran and the bomb may have entered a new stage but is far from over.