The Iran nuclear program's heavy-water reactor at Arak. Photo: Wikimedia Commons.

A New York Times report on Tuesday that Iranian nuclear fuel stockpiles have grown 20 percent over the last 18 months further called into question Iranian goodwill over a deal with world powers over its nuclear program.

The report, citing the International Atomic Energy Agency (IAEA), also calls into question one of the Obama administration’s main arguments for continuing to pursue the June 30 deadline for a nuclear deal based on the Lausanne framework hammered out by negotiators in April, namely that Iran had frozen its fuel production following an interim agreement in late 2013.

“Contrary to the relevant resolutions of the Board of Governors and the Security Council, Iran has not suspended all of its enrichment related activities in the declared facilities,” said the report released by the IAEA last Friday.

And according to the Times, Western officials and experts “cannot quite figure out why” Iran continues to boost its nuclear fuel stockpiles.

One explanation was that Iranian scientists ran into difficulties converting enriched uranium into fuel rods, which cannot be used to develop nuclear weapons.

Another possible explanation is that the Iranians want a larger stockpile to serve as a bargaining chip should the deal fall through, which is especially relevant as any nuclear deal will ultimately include the lifting of sanctions against Iran.

Once sanctions are lifted, firms and nations around the globe would be free to start doing business in Iran, which critics of the deal say would tie the international community’s hands in reimposing sanctions should Iran cheat on the nuclear deal.

“That’s exactly the problem with dropping the sanctions before Iran has proved any goodwill,” said an Israeli diplomatic source earlier this week. “The Americans are going to be doing business with Iran, and the Austrians and the Germans and the French and the whole world is going to do business with Iran.”

The IAEA report also said the agency “remains concerned about the possible existence in Iran of undisclosed nuclear-related activities involving military related organizations, including activities related to the development of a nuclear payload for a missile.”

On Monday, Russia announced it was starting construction on a second nuclear plant in Iran.

Responding to the IAEA report, nongovernmental organization The Israel Project said, “Iran has violated every nuclear-related treaty it has ever signed, and [President Barack Obama] has spoken of giving them a $150 billion signing bonus for the impending deal that will undermine American leverage to enforce the upcoming deal.”

Obama and Secretary of State John Kerry, who flew back to the U.S. for treatment of an injury he sustained during a cycling accident in Switzerland, still must sell the deal to Congress. According to the Times, this includes convincing lawmakers that Iran would shrink its stockpile by 96% just a number of months after the deal is signed.

“The violations will be brushed off,” said The Israel Project. “The administration will say the Iranians still have time to hit their targets, which is the same game that administration officials played with Iran cheating on oil export caps.”