(Bloomberg) -- Iran has re-installed monitoring equipment and boosted its cooperation with international inspectors even as its engineers added to stockpiles of uranium enriched closer to weapons grade, the global nuclear watchdog reported Wednesday. 

The findings published in the International Atomic Energy Agency’s quarterly report on Iran reduces the likelihood that the Islamic Republic will face censure when diplomats convene June 6 to discuss its nuclear program.

IAEA inspectors had raised concerns in March over the presence of uranium particles enriched to 84% levels of purity and chided Iran’s slow response to separate investigations, raising the prospect of worsening tensions in the Middle East. 

On Wednesday, agency inspectors wrote they “had no further questions” about the presence of those highly-enriched particles and accepted Iran’s explanation.

Iran is already at the center of several overlapping geopolitical crises, including the effective suspension of its nuclear talks with world powers, its military support for Russia’s war on Ukraine and the recent seizure of ships near the narrow entrance to the Persian Gulf.

“Some progress has been made,” IAEA Director General Rafael Mariano Grossi wrote in one of two restricted reports published Wednesday. “Iran has provided a possible explanation for the presence of depleted uranium particles. Iran has allowed the agency to install some additional surveillance cameras”

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Iran’s stockpile of uranium enriched to 60% levels of purity reached 114.1 kilograms (251.6 pounds) a significant increase from the 87.5 kilograms documented in the last report at the end of February. Inventories of 20%-enriched fuel grew to 470.9 kilograms from 435 kilograms. 

It’s the tenth consecutive quarter that Iran has added to its reserve of nuclear fuel enriched to 60%, despite suffocating US sanctions. That purity is still below the 90% grade typically used for weapons, but much higher than the 300 kilograms at 3.67% purity cap set by the now-defunct nuclear accord. 

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While Iran has always maintained its atomic work is peaceful, world powers negotiated the nuclear pact with the Persian Gulf nation in 2015 because they doubted that claim. 

The so-called JCPOA limited Iran’s nuclear activities and imposed unprecedented monitoring in return for sanctions relief. But the Trump administration withdrew from the deal in 2018, reimposing sanctions and prompting Iran to cease compliance. Diplomats have subsequently failed to restore its provisions. 

Iran’s re-installation of monitoring equipment is significant because it will help preserve data IAEA monitors need to reconstruct certain nuclear activities, should another agreement with world powers be struck. The prolonged absence of monitoring at some Iranian sites means inspectors will have to start from square one in reconstructing knowledge. 

“The agency would not be able to re-establish continuity of knowledge in relation to the production and inventory of centrifuges,” read the report. “Instead, the agency would need to establish a new baseline.”

IAEA inspections of Iran fell about 10% last year but remained well above monitoring levels before the 2015 nuclear agreement, a separate report circulated among diplomats earlier this month found. 

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