Iran announced on Monday that it had breached the limits for stockpiling low-enriched uranium set by the 2015 nuclear deal. This was the first time the Islamic Republic was violating the terms of the multilateral agreement, which had set a 300-kg cap for Iran’s enriched uranium stock.

A few days later, Iran announced that it would breach another crucial term of the deal: the enrichment limit. For now, Iran is allowed to enrich uranium to 3.67% purity.

Why is Iran breaching the terms of the deal?
The current crisis was set off by Mr. Trump when, in May 2018, he unilaterally pulled the U.S. out of the nuclear deal and reimposed sanctions on Iran. The deal had promised to lift all international sanctions on Iran in return for the country scuttling its nuclear programme. With sanctions by the U.S. back, Tehran turned to other signatories to save the deal. Countries that had stepped up buying Iranian oil after the deal was signed, including India, started cutting back on imports. As a result, Iran’s oil exports plummeted. Iran now exports about 230,000 barrels of crude a day, down from 2.5 million barrels a day in May 2018. Inflation has soared to 35%, while the rial, the Iranian currency, has fallen by 70% since early 2018.

Faced with tough choices, Iran decided to confront the U.S. and put pressure on other signatories to take bold steps to save the deal rather than capitulating to American pressure. The nuclear deal is a crucial bargaining card, and Tehran has decided to use it as a pressure tactic.

Could Iran make the bomb?
There are two paths to the bomb. One is using uranium and the other using plutonium. In the first, uranium is enriched to the weapons grade level using centrifuges. The enrichment increases the fraction of that isotope of uranium which makes up the bomb. In the second method, plutonium, produced as a waste material by heavy water reactors, will be reprocessed to enhance its purity.

When the deal was signed in 2015, Iran had a stockpile of 11,560 kg of low-enriched uranium. It had also enriched uranium to 20% purity. According to nuclear experts, if Iran can produce uranium to 20% purity, it is possible for the country to make the weapons-grade fuel — at 90% purity. Iran had also possessed some 20,000 centrifuges in 2015. In Arak, it was building a heavy water reactor. The nuclear deal has substantially reduced these capabilities. It set the enrichment limit at 3.67% and the limits to the low-enriched uranium stockpile at 300 kg. Under the deal, Iran had also placed two-thirds of its 20,000 centrifuges in storage, besides removing the core of the Arak heavy water reactor and fill it with concrete. The plan was to enhance the break-out time (the time required to build a bomb if Iran resumes its nuclear programme in its full potential) to at least a year. Now that its stockpile of uranium is rising and it is threatening to enrich high purity uranium, at least in theory, the distance between Iran and the bomb is shrinking. If Iran continues to violate the deal, redeploying the centrifuges and resuming construction of the Arak facility could be its next steps. That would allow Iran to reload its nuclear programme in full capacity.

What is next?
Both the U.S. and Iran are currently on a confrontational path, while other signatories to the deal call for a diplomatic solution to the crisis. The Trump administration wants Iran to return to talks on the U.S.’s terms. The reason Mr. Trump withdrew the U.S. from the deal was that he believed it was a “bad deal” that does not address Iran’s ballistic missile programme and its “subversive” activities in West Asia such as backing proxy militias. So Washington wants to negotiate an agreement that addresses all these issues.

Iran, on the other side, sees the Trump administration as the main disruptor of the deal and instigator of tensions in the Gulf. It wants either the U.S. to return to the deal or other signatories to save it sans the U.S.