According to a report from the United Nations’ nuclear watchdog, Iran has amassed more than “the approximate amount of nuclear material for which the possibility of manufacturing a nuclear explosive device cannot be excluded”. In a separate International Atomic Energy Agency (IAEA) report seen by Reuters Monday, Iran has not adequately explained the origin of uranium particles found at three undeclared sites.

“Iran has not provided explanations that are technically credible in relation to the Agency’s findings at those locations,” the report said. “The Agency remains ready to engage without delay with Iran to resolve all of these matters.”

Iran responded to the report Tuesday, calling it “not fair and balanced.” A spokesperson for the Iranian foreign ministry said the blame for this lies with Israel.

“It is feared that political pressure by the Zionists and others have made the reporting deviate from technical direction to political direction,” Saeed Khatibzadeh said. “We expect that this behavior is corrected.”

Iran’s response to the report comes the same day Israel said it has proof that Iran stole classified documents from the nuclear watchdog nearly two decades ago. Israel accused Iran of using the documents to conceal its nuclear activities from international inspectors.

“Iran used that information to figure out what the Atomic Agency was hoping to find, and then created cover stories and hid evidence to evade their nuclear probes,” Israeli Prime Minister Naftali Bennett said Tuesday. “So how do we know this? Because we got our hands on Iran’s deception plan a few years back.”

Prime Minister Bennett circulated the documents to media. His office said they came from a trove of Iranian nuclear files seized by Israel in 2018 but have not previously been made public.

“There is even some handwritten notes on the documents by senior Iranian officials — like this one, written by then-defense minister Fakhrizadeh,” Bennett said. “He writes, ‘Sooner or later they – referring to the Atomic Agency – they will ask us, and we’ll need to have a comprehensive cover story for them.’”

Tuesday’s developments come as talks to restore Iran’s nuclear deal have been stalled for months. On Tuesday, Iranian Foreign Minister Hossein Amirabdollagian said he expressed concerns over the negotiations to Vice President Kamala Harris when they were in Munich earlier this year.

Iran has demanded guarantees that no future U.S. president could abandon the deal, like former president Donald Trump did in 2018. The White House has said it can’t make such a guarantee.

The Associated Press contributed to this report.