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How the Iran Deal Blocked a Nuclear Bomb in Two Charts

The Charts Show a Dramatic Decrease in Stockpiles as Soon as the Deal Was Implemented

The 2015 Iran Deal, negotiated by the Obama administration, blocked Iran’s paths to a nuclear weapon by placing a series of restrictions on Iran’s nuclear research and stockpiles, and enacting a slew of monitoring, verification and oversight mechanisms. 

One of the most significant elements of the deal was its ban on highly enriched uranium.

To make a nuclear weapon, you need highly enriched, weapons-grade uranium. Low enriched uranium is used for a range of peaceful purposes, including nuclear energy, but can also be transformed into highly-enriched uranium through further processing.

Uranium is considered “highly enriched” when concentration reaches above a 20% threshold, and “weapons-grade” when it reaches is above 90%.

Under the agreement, Iran was totally banned from enriching any uranium above a 3.75% threshold. Iran’s low enriched uranium stockpile was also capped at 300kg, less than the amount necessary to refine further into enough weapons-grade material to make a bomb. 

As part of the agreement, Iran had to ship out a significant amount of its pre-agreement stockpile to get back down to those levels. 

Here’s what that looked like: 


Highly Enriched Uranium



Low Enriched Uranium

What’s significant in those graphs isn’t just the sudden decrease in stockpiled uranium in 2014 (of HEU) and 2015 (of LEU) thanks to the interim and final deals, respectively – which has a significant impact on breakout time and weapons capability – but that the stockpile of low enriched uranium creeps back up in 2019 and 2020, with HEU stockpiles following thereafter.

That’s because in 2018, President Trump withdrew from the multilateral agreement, a decision which enabled Iran to gradually withdraw from oversight mechanisms and increase nuclear stockpiles. 

International inspectors now struggle to gain the same level of access to nuclear sites. 

“Looking at the policy on Iran in the last decade, the main mistake was the withdrawal from the agreement,” said Moshe Yalon, Israel’s Defense Minister from 2013 to 2016. “It gave them an excuse to go ahead.”

With Iran now resuming its uranium enrichment programs above the limits of the original deal, it’s more urgent than ever that the United States work to restore caps and restrictions and resume the strict monitoring and oversight mechanisms in place under the original deal. 

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