A year ago, Iran had enough enriched uranium to build nine nuclear devices and would have been able to enrich enough material to create its first nuclear device within roughly six weeks. It was enriching uranium in the fortified Fordow facility in the heart of a mountain, and had installed 19,000 centrifuges, 9,000 of which were active.
Furthermore, Iran was introducing advanced centrifuges that would multiply the rate at which it enriched uranium, and in Arak it was putting the finishing touches on a reactor that would enable production of weapons-grade plutonium.
Thanks to the deal, the Iranian nuclear program has been rolled back and is now at least a year away from obtaining a nuclear device. Indeed, the deal ensures Iran will be kept a year away from the bomb for another ten years. Its stockpile of enriched uranium is now capped at 300 kilograms — less than a third the amount required for a bomb. Most of Iran’s centrifuges have been dismantled. No uranium is allowed in Fordow and advanced centrifuge R&D is and will remain severely limited for nearly a decade. Moreover, Iran must allow inspectors access to suspected undeclared sites within a limited timeframe. The core of the Arak reactor has been removed and filled with concrete.
In short, Iran is considerably farther from military nuclear capability and under stricter oversight and verification than it would have been without the deal, as it will remain for years to come. This is a much better outcome than those offered by the alternatives, including the use of military force.
Avishay Ben Sasson-Gordis, “A Year In: Iran Is Still Bad, the Iran Deal Is Still Good”, Jewish Journal (29 July – 4 August 2016), 12.