As outlined by President Obama at a news conference this afternoon, the tentative nuclear agreement reached with Iran appears to include significant concessions that will achieve the most important metric demanded by the United States and its diplomatic partners — namely, to extend the “breakout” period required for Tehran to develop a single nuclear weapon. The full deal is complex and yet to be completed, but the highlights seem to answer the most pressing concerns about a sustainable and verifiable non-proliferation regime.

According to the president and negotiators in Lausanne, Switzerland, where the talks had continued into the early hours today, the government of Iran has agreed to cut its uranium-enriching centrifuges from 19,000 to 6,000, greatly reducing its capacity to rapidly produce weapons-grade material. For the next 10 years, only about 5,000 of those centrifuges will actually operate at all. The excess centrifuges and related machinery will be held in storage monitored by the International Atomic Energy Agency, to be used only for replacement parts — and Iran will construct no new uranium-enrichment facilities for the duration of the agreement.

Taken together, these changes are expected to extend the “breakout” period from a few months to at least one year.

Iranian foreign minister Javad Zarif also agreed that his country would not enrich uranium over 3.67 percent for the next 15 years and will slash its present inventory of more than 20 tons of low-enriched uranium to well under a ton for the same duration. Moreover, Zarif and his team conceded that Iran will ship all the spent fuel from its heavy-water reactor at Arak, which might have been reprocessed into bomb-ready plutonium, to other countries for reprocessing — a sticking point earlier in the talks. The Arak facility itself will undergo a reconstruction process — including the destruction of the reactor’s original core — that will make production of plutonium there impossible, and Iran will construct no further plants capable of producing plutonium for at least 15 years.

The deal provides for continuous IAEA monitoring of all Iranian nuclear reactors and programs — described by Obama as the most intensive ever undertaken — and for sanctions relief that will only begin when Iran has met all of its initial commitments to restructure and dismantle its weapons-related equipment and programs. It also includes restrictions on certain kinds of conventional weapons and technology.

As the president said with his usual lucidity, these negotiations — and their ultimate success — are an opportunity of historic significance to reduce the risks of war and proliferation.

But the Iran talks also represent a chance to promote peaceful change in that unfortunate country, whose people desperately hope that the Rouhani government can progress toward normal relationships with Western countries, especially the United States. The best guarantees of peace and security — for the world, the U.S., the Mideast region, and yes, Israel — will be realized by strengthening the forces in Tehran that seek to transcend Iran’s status as diplomatic and economic pariah.

Partisan efforts to scuttle the nascent bargain have long been underway, and will now intensify. The perpetrators are almost exclusively “experts” who were wrong about very similar issues concerning the supposed nuclear ambitions of Iraq — and led us into a pointless war that cost many thousands of lives and trillions of dollars. The American people support President Obama’s use of internationally backed sanctions to encourage a negotiated agreement rather than armed conflict — and his approach is proving more effective than the belligerent attitude promoted by his critics over the past decade. Let us hope that he and Secretary of State John Kerry, both of whom deserve enormous credit for their moral courage and pertinacity, will be able to bring forth a signed agreement by the next deadline in late June.

Photo: U.S. Department of State via Flickr