A little over a year after President Donald Trump withdrew the U.S. from a landmark nuclear agreement with Iran, Tehran’s government responded by breaking a key covenant restricting its stockpile of nuclear material. International inspectors confirmed that the country has accumulated more than the 300 kilograms of low-grade uranium permitted under the 2015 accord. Although the initial violation was limited and can easily be reversed, Iran said on July 7 that it will restart other, more serious atomic activities unless Europe, China and Russia step up with economic relief. Those steps could provide Iran with a path to nuclear weapons.

1. How close is Iran to making a bomb?

It would take Iran a while to accumulate the necessary materials. The 2015 accord was designed to ensure that even if Iran broke out of the deal, it would need at least a year to restore the capacity and material needed for a weapon. Iran forfeited some 97% of its enriched uranium and mothballed three-quarters of the industrial capacity needed to refine the heavy metal. International Atomic Energy Agency inspectors, who, thanks to the agreement, are on the ground daily to conduct real-time monitoring, report the country has less than half of the 1,050 kilograms of low-enriched uranium that would be needed to construct a single weapon. Before the accord, Iran had enough to potentially build more than a dozen bombs. While the country always maintained its program was civilian, world powers pursued the deal because they doubted that claim.

2. How could Iran escalate this crisis?

Iran has two levers it can use to raise pressure. It has already triggered one by exceeding the uranium-stockpile cap and it’s pulling another. President Hassan Rouhani warned that his country would no longer be bound by the agreement not to enrich uranium beyond a 3.67% concentration of uranium-235 isotopes, a level used for nuclear power. Officials confirmed on July 7 that they’d breached that limit, potentially reducing the time needed to produce weapons-grade material if the Islamic Republic decides to do so. Most nuclear bombs are made with uranium enriched to 90%. Trump tweeted the move could “come back to bite you like nobody has been bitten before!”

3. Why is enrichment so important?


Obtaining the material necessary to induce atomic fission is the most difficult step in the process of making nuclear power or bombs. Countries need to develop a vast industrial infrastructure to produce uranium-235 isotopes, which comprise less than 1% of matter in uranium ore but are key to sustaining a fission chain reaction. Thousands of centrifuges spinning at supersonic speeds are used to separate the material. The IAEA keeps track of gram-level changes in uranium inventories worldwide to ensure the material isn’t being diverted for weapons. Whether or not Iran retains the right to enrich uranium has been at the heart of its nuclear conflict with the U.S. for two decades.

4. Why is Iran breaking the deal?

U.S. sanctions reimposed after Trump withdrew from the accord are causing Iran’s economy to sink and its leadership to dig in. The country’s leaders are rejecting new negotiations unless Iran regains the ability to trade oil and other goods. In the absence of compromise, Tehran has a range of other measures it could use to escalate, from increasing enrichment capacity to curtailing inspections. While Iran’s leaders may see stepping up nuclear activities as a way to regain leverage negotiated away in the 2015 deal, escalation could backfire and condemn Iran to political isolation, or even result in military conflict.

5. What are these other steps?

Iran is already talking about restarting construction of a heavy-water reactor that could produce plutonium, potentially opening another path to amass fissile material for a bomb. That decade-long project was disabled by the accord and would need significant work to reconstitute. The country could also break seals on thousands of mothballed centrifuges and begin introducing more advanced machines to enrich uranium faster. If it withdraws from the accord entirely, Iran could end the special access given to IAEA inspectors and curtail their powers to call surprise visits. In the worst case, it could even withdraw altogether from the nuclear Non-Proliferation Treaty, the multilateral 1968 accord meant to thwart the spread of nuclear arms. That’s what North Korea did three years before testing its first bomb.

6. How might other countries react?

Iran’s violation of its nuclear covenants has set high-stakes diplomacy in motion and could lead to a meeting of foreign ministers from China, France, Germany, Russia and the U.K. If those remaining parties to the agreement can’t convince Tehran to reverse course, Iran could be referred to the United Nations Security Council, where it would face broader international sanctions. The European Union could also decide to reapply its own penalties. China and Russia may opt to provide economic and political cover by helping Iran dodge sanctions and exercising their UN veto power. As for Trump and the U.S., expect saber rattling to replace the threat of sanctions as U.S. penalties tighten around the whole of Iran’s economy.

To contact the reporter on this story: Jonathan Tirone in Vienna at jtirone@bloomberg.net

To contact the editors responsible for this story: Reed Landberg at landberg@bloomberg.net, Andy Reinhardt, Lin Noueihed

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