Context: Amid escalating tensions with the United States, Iran has said that it would surpass the limit on the uranium supply permitted under the 2015 nuclear agreement, a potentially combustible new phase in the country’s confrontation with Washington.

Iran’s response:

Iranian leaders have sought to justify these steps as a response to the Trump administration’s abandonment of the nuclear accord last year and its reimposition of sanctions, which have weakened Iran’s economy and in particular choked its ability to sell oil, the country’s most important export.

Iran insists its nuclear work remains peaceful, as guaranteed under the accord. But Iran also insists that the country has the right to stop honoring some or all of provisions because the United States has reimposed sanctions in violation of the accord.

Why is this a cause for concern?

Iran is permitted to keep up to 300 kilograms, or about 660 pounds, of uranium enriched to 3.67% purity, a level that can be used for civilian purposes like nuclear power fuel.

Iran would need roughly triple the amount of 3.67%-enriched uranium it is permitted to possess under the accord in order to further enrich the material into weapons-grade strength sufficient to make one bomb.

Iran has said that it is quadrupling production of low-enriched uranium, raising the possibility they could start stockpiling far greater quantities again.

What is the iran nuclear deal?

Iran agreed to rein in its nuclear programme in a 2015 deal struck with the US, UK, Russia, China, France and Germany.

Under the Joint Comprehensive Plan of Action (JCPoA) Tehran agreed to significantly cut its stores of centrifuges, enriched uranium and heavy-water, all key components for nuclear weapons.

The JCPOA established the Joint Commission, with the negotiating parties all represented, to monitor implementation of the agreement.

Why did Iran agree to the deal?

It had been hit with devastating economic sanctions by the United Nations, United States and the European Union that are estimated to have cost it tens of billions of pounds a year in lost oil export revenues. Billions in overseas assets had also been frozen.

Why has US pulled out of the deal now?

Trump and opponents to the deal say it is flawed because it gives Iran access to billions of dollars but does not address Iran’s support for groups the U.S. considers terrorists, like Hamas and Hezbollah. They note it also doesn’t curb Iran’s development of ballistic missiles and that the deal phases out by 2030. They say Iran has lied about its nuclear program in the past.

Impact of escalated tension between Iran and the US:

• Iran can make things difficult for the U.S. in Afghanistan as also in Iraq and Syria.
• The U.S.’s ability to work with Russia in Syria or with China regarding North Korea will also be impacted.
• And sooner or later, questions may be asked in Iran about why it should continue with other restrictions and inspections that it accepted under the JCPOA, which would have far-reaching implications for the global nuclear architecture.
• Coming after the rejection of the Trans-Pacific Partnership (TPP), the Paris climate change accord and the North American Free Trade Agreement, President’s decision further diminishes U.S. credibility.

What role does the U.N. Security Council play in this crisis?

The Security Council adopted a resolution in 2015 that endorsed the nuclear agreement and ended U.N. sanctions against Iran. The resolution, 2231, includes what is known as a “snapback” provisionthat could reinstate those sanctions if other parties to the agreement complained that Iran was cheating. Such a step would likely doom the agreement.