The US State Department’s lead negotiator on Iran’s nuclear program suggested Wednesday that the US would push the Islamic Republic to dismantle part of its Arak nuclear reactor as part of a final agreement.

A comprehensive agreement “includes a lot of dismantling of their infrastructure,” Under Secretary of State for Political Affairs Wendy Sherman said in an interview on the PBS network.

“Because, quite frankly, we’re not quite sure what you need a 40-megawatt heavy water reactor — which is what Arak is — for any civilian peaceful purpose.”

Iran has said that it will continue with construction at the Arak reactor for the duration of an interim agreement reached with the P5+1 in Geneva last month. However, the Islamic Republic has indicated that it will not increase the facility’s capacity or produce more nuclear fuel there while the deal was in place.

The Arak reactor became a significant stumbling block during the Geneva talks, where Iran agreed to limit its nuclear program in exchange for an easing of crippling economic sanctions. The interim agreement has yet to be finalized.

When operational, the Arak facility could produce plutonium, one of two substances that can form the core of a nuclear weapon. The other is enriched uranium. The White House said Tuesday that a final deal with Iran could include the capacity for some uranium enrichment.

“We are prepared to negotiate a strictly limited enrichment program in the end state, but only because the Iranians have indicated for the first time in a public document that they are prepared to accept rigorous monitoring and limits on level, scope, capacity, and stockpiles,” Bernadette Meehan, the National Security Council spokeswoman, said in a statement Tuesday to JTA, in response to a query arising from a story first reported by the Washington Free Beacon.

It has been reported for months that the Obama administration and Western powers were prepared to tolerate low level enrichment as part of a permanent deal; Meehan’s statements Tuesday were the first on-the-record confirmation.

Israel opposes any permanent enrichment capacity, saying that at even low levels, the infrastructure required for such enrichment leaves Iran perilously close to the ability to manufacture a weapon.

“If we can reach an understanding on all of these strict constraints, then we can have an arrangement that includes a very modest amount of enrichment that is tied to Iran’s actual needs and that eliminates any near-term breakout capability,” Meehan said. “If we can’t, then we’ll be right back to insisting on no enrichment.”

Sherman told PBS’s Gwen Ifill that Washington was communicating “all of the time” with Jerusalem regarding Israeli concerns about a deal with Iran.

“Israel, the United States and all the Gulf states share the same objective: Iran will not, cannot, shouldn’t have a nuclear weapon. The president has been very clear that he will stop that from happening. So we agree on the objective. Tactically, we may disagree from time to time,” she said.