“Destroying centrifuges is more disruptive than damaging anything else,” James Walker, CEO of Nano Nuclear Energy, said to the Mirror US, highlighting a reality that recent U.S. intelligence has made painfully clear: Iran’s central uranium enrichment equipment made it through the most recent airstrikes, contrary to prior reports of full destruction. For policy observers and non-proliferation experts, this technical nuance is anything but academic it resets the global risk equation.
The gas centrifuge is still the backbone of uranium enrichment. The machines, by rotating uranium hexafluoride (UF6) gas at breathtaking velocities, take advantage of the minute mass variation between uranium-235 and uranium-238 isotopes. Newer cascades, particularly the latest IR-2m and IR-6 designs, have continuously replaced the aging IR-1 machines, exponentially boosting Iran’s enrichment capacity. Up to February 2025, Iran was running more than 80 cascades of centrifuges at Natanz and Fordow, including thousands of new-generation ones, based on the International Atomic Energy Agency (IAEA) and technical detailed analyses.
Enrichment is sequential. Natural uranium with only 0.7% U-235 needs to be refined through several cascades in order to achieve reactor-grade (3-5%), medical-grade (20%), and most importantly, weapons-grade (90%) enrichment. Iran’s 60% enriched uranium stockpile already a huge technical advance would have “over 90% of the work needed to bring natural uranium to weapon-grade” done, according to Iran Watch analysis. The technical challenge is not beginning from scratch but maximizing current cascades and tweaking flow rates and configurations to get that last goal increment up to 90%. Walker observes, “If the centrifuge cascade is already enriching to 60%, then the hardware…is likely capable of enriching to 90% with modifications to the cascade design and flow.”
Timeframes for this last step of enrichment are breathtakingly brief. U.S. Central Command’s General Michael Kurilla explained that, if Iran chose to “sprint” to a bomb, it would be able to produce as much weapons-grade uranium as is needed for a rudimentary device in one week and as much as ten weapons’ worth in three weeks a conclusion shared by several intelligence estimates. But manufacturing the fissile core is only half the process. The uranium, originally in gaseous UF6 form, has to be reduced to metal, cast and machined into weapons components a technically complex task, but one that Iran has allegedly sought since 2021.
Weapon design introduces added complication. The Hiroshima weapon, “Little Boy,” employed some 64 kilograms of highly enriched uranium in a straightforward “gun-type” assembly, with a yield of approximately 16 kilotons. Contemporary fission bombs, on the other hand, utilize implosion models that need minimal material from 7 to 16 kilograms of 90% enriched uranium and are more efficient and compact, technical sources say. Still, as Walker points out, “the ones that actually were used on Japan weren’t particularly powerful by the standards of modern weapons.” Modern thermonuclear (hydrogen) bombs, on the other hand, employ a fission igniter to start a fusion phase and achieve yields thousands of times larger Tsar Bomba, for instance, came to 50 megatons, hundreds of times larger than the destructive potential of first-generation atomic bombs as depicted in recent analysis.
International monitoring has become more difficult. Iran since 2021 has limited IAEA access to sites of great importance and expelled monitoring equipment, having inspectors depend on fragmented information and sporadic declarations. The chance of being able to breakout undetected at secret sites is increasing as Iran’s centrifuges are becoming more productive and use less space 3,000 IR-2m centrifuges can enrich sufficient uranium for a bomb within four months in an area only two times the size of a hockey rink.
The arms race is now in weeks and months, rather than years. While no Iranian leader has publicly sanctioned a nuclear weapons program, U.S. intelligence and IAEA documents indicate that all the technical obstacles to weaponization have been methodically eliminated. As Secretary of State Marco Rubio told CBS News, “They have everything they need to build nuclear weapons.” The question for international security is no longer whether Iran can construct a bomb, but how quickly it might and whether the world would see the last steps in time.
