Inspectors from the United Nations nuclear watchdog found uranium particles enriched up to nearly 84 percent in Iran's underground Fordow uranium enrichment site, International Atomic Energy Agency (IAEA) Director-General Rafael Grossi confirmed on February 28.
Grossi confirmed that the uranium particles had a purity level of 83.7 percent, which is just below the 90 percent purity needed for nuclear weapons, raising concerns that Iran could quickly use the material to produce an atomic bomb.
The traces were discovered in January during an inspection of the Fordow uranium enrichment plant, and the IAEA is in discussions with Iran to clarify their origin.
The Iranian authorities explained to the IAEA that the extremely high enrichment level is the result of "unintended fluctuations."
A spokesman for Iran's civilian nuclear program, Behrouz Kamalvandi, sought last week to portray any detection of uranium particles enriched to the level of 84 percent as a momentary side effect of trying to reach a finished product of 60 percent purity.
However, experts say such variance in the purity would appear suspicious to inspectors.
The information about the discovery of the particles is contained in a confidential quarterly report by the IAEA that leaked out earlier on February 28.
The 2015 nuclear deal, which the U.S. withdrew from in 2018, limited Tehran’s uranium enrichment to 3.67 percent -- enough to fuel a nuclear power plant. Talks to revive the deal have been frozen for months.
Grossi warned in January that Iran now has enough uranium to produce "several" nuclear bombs if it chooses. But it likely would take months more to build a weapon and potentially miniaturize it to put it on a missile.
Tehran has always stressed that it is only interested in peaceful nuclear technology.
The report also said Iran has almost 435 kilograms of uranium at 20 percent purity. That is 48 kilograms more than in the previous quarterly report in November.
The stockpile of 60 percent uranium increased by 25 kilograms and currently stands at just under 88 kilograms, according to the report. Nonproliferation experts have said Tehran has no civilian use for uranium purified to the level of 60 percent.
German Foreign Minister Annalena Baerbock said both her country and Israel are worried about the reported 84 percent enriched uranium.
"We are united by concern about the nuclear escalation on Iran's part and about the recent reports about the very high uranium enrichment," Baerbock said on February 28. "There is no plausible civilian justification for such a high enrichment level."
Israeli Foreign Minister Eli Cohen, who is visiting Berlin, said there were two options to deal with Iran: reimposing UN sanctions using the so-called snapback mechanism in the Security Council resolution that enshrined the 2015 nuclear deal or having a "credible military option on the table."
He said based on Israeli intelligence "this is the right time to work on these two specific steps."