VIENNA — Iran has converted three-quarters of a nuclear stockpile that it could have turned quickly into weapons-grade uranium into less volatile forms and is well on the way toward transforming the rest, the UN atomic agency reported Thursday.
The development — agreed to by Iran under a nuclear deal it struck late last year with six world powers — leaves Tehran with substantially less of the 20-percent enriched uranium that it would need for a nuclear warhead. Iran denies any interest in atomic arms. But it agreed to some concessions in exchange for a partial lifting of sanctions crippling its economy under the deal.
Uranium at 20 percent is only a technical step away from weapons-grade material. By the time the agreement was reached last year, Iran had amassed nearly 440 pounds. With further enrichment, that would have yielded almost enough for one atomic weapon — a threshold that Israel had vowed to prevent Iran from reaching.
Iran agreed to stop enriching to grades beyond 5 percent, used to power reactors.