The JCPOA did limit Iran’s immediate ability to enrich enough uranium for a bomb. It reduced the regime’s uranium stockpile by 97 percent, mothballed two-thirds of its centrifuges, and re-designated two of its major nuclear facilities as civilian research centers. Uranium enrichment was capped at 3.7 percent, far short of weapons-grade. These concessions were intended to extend the time Iran needed to enrich enough uranium for a single bomb from approximately three months to a year. Should Iran attempt to break out and go nuclear, advocates explained, the international community would have enough time to intervene. The JCPOA, they asserted, blocked all of Iran’s paths to a bomb.

But the JCPOA allowed Iran to retain its massive nuclear infrastructure, unnecessary for a civilian energy program but essential for a military nuclear program. The agreement did not shut down a single nuclear facility or destroy a single centrifuge. The ease and speed with which Iran has resumed producing large amounts of more highly enriched uranium—doing so at a time of its own choosing—illustrates the danger of leaving the regime with these capabilities. In fact, the JCPOA blocks nothing.

If the restrictions on Iran’s nuclear enrichment were inadequate, they were also designed to be short-lived, some sunsetting as early as 2024. Meanwhile, the deal allowed the regime to develop advanced centrifuges capable of spinning out more highly enriched uranium in far less time. Less than a decade from now, Iran will be legally able to produce and stockpile enough fissile material for dozens of bombs.