Q1: What exactly did Iran do?

A1: Iran announced Monday—and international inspectors confirmed—that it had exceeded the amount of enriched uranium it can have on hand under the terms of the nuclear deal (known as the Joint Comprehensive Plan of Action or JCPOA). The deal allows Iran to have up to 300kg of up to 3.67 percent enriched uranium hexafluoride. Iran has reportedly only gone over that limit by a few kilograms. The cap on the amount of material Iran can have is only one of many limits that the deal imposes on Iran’s enrichment program.

Q2: Does this make it easier for Iran to build a nuclear weapon?

A2: Iran’s breach of these limits does not pose any immediate proliferation risk. The amount of material Iran has produced is still modest and is only a fraction of the amount that it would need for a nuclear weapon, which Iran would then need to further enrich to higher levels.

If Iran continues to grow its stockpile, however, it will begin to reduce the amount of time Iran would need to produce enough fissile material for a weapon (commonly referred to as Iran’s “breakout timeline”). This breakout timeline currently stands at a year because of the limits imposed by the nuclear deal. It’s worth recalling that before Iran’s implementation of the JCPOA and its interim predecessor, the Joint Plan of Action, Iran had amassed enough material for about 10 nuclear bombs, and its breakout timeline was roughly 2-3 months. Iran is also unlikely to dash to a nuclear weapon using this material because under the terms of the deal, international inspectors have routine access to its declared nuclear facilities and would quickly detect and report it, enabling international action.

Q3: So, if not for a bomb, why did Iran do this—and why now?

A3: By its own admission, Iran is taking these steps in response to U.S. sanctions that have made it impossible for Iran to reap the economic benefits of the deal, namely sanctions on Iranian banking and oil exports. Although European participants in the deal were able to activate a channel last week to facilitate trade between Europe and Iran for non-sanctioned goods, Tehran deemed this insufficient. By resuming some nuclear activities, Tehran is trying to pressure the United Kingdom, France, Germany, and other members of the European Union to go further and regain negotiating leverage if and when it finds itself back in talks with the United States. This action was not a surprise. In May, Iranian president Hassan Rouhani announced that if economic benefits were not forthcoming, then Iran would slowly begin unwinding some of its nuclear commitments starting with the cap on uranium.

Q4: What happens next? How will the international community and United States respond?

A4: Iran has threatened to begin enriching uranium to higher levels as soon as July 7, which would be far more problematic and provocative than breaching the 300kg stockpile limit, if remaining participants in the deal fail to take steps to restore trade and confront U.S. sanctions. If Iran follows through, this has the potential to more quickly shorten Iran’s breakout timeline.

European participants in the deal, which have warned Iran not to go down this path, will need to decide whether and how hard to press Iran to reverse course and what if any penalties they want to impose. Doing so risks provoking further Iranian nuclear advancements and could ultimately cause the deal to unravel—an outcome Europe is keen to avoid.

The United States, no longer a member of the nuclear pact, has intimated that any nuclear advancements by Iran that reduce its breakout timeline are unacceptable but has left unsaid what those consequences would be.

Given that the most damaging sanctions measures have already been employed by the United States, there are few tools short of military action that Washington could use to deter Iranian nuclear advances—and using military force to prevent a mere shortening of Iran’s breakout timeline would be a strategic error with significant negative ramifications. President Trump has stated that he is willing to talk to Iran without preconditions, providing a potential opening for dialogue. But Washington, at a minimum, would need to significantly moderate its tone and probably put a pause on any new pressure tactics for talks to be political palatable in Iran.

Eric Brewer is deputy director and fellow with the Project on Nuclear Issues at the Center for Strategic and International Studies in Washington, D.C.

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