(Bloomberg) -- The U.S. is asking other countries to support a formal censure of Iran over its accelerating nuclear activities, a signal that the Biden administration wants to turn up the diplomatic heat on Tehran as it looks to restore a crumbling 2015 accord.

The International Atomic Energy Agency’s board of governors convenes next week in Vienna to discuss the latest reports that Iran has stepped up production of nuclear fuel while stalling inquiries into the presence of uranium particles at undeclared sites.

U.S. diplomats circulated a document on Thursday which lists Washington’s grievances and orders Iran to fully cooperate with inspectors. The proposed resolution would “underscore strong concern at the IAEA’s findings” and “express the board’s deepening concern with respect to Iran’s cooperation,” read the three-page document seen by Bloomberg.

A State Department spokesman declined to comment. Two European officials confirmed they received the document and said they were studying its contents.

Next week’s meeting could become a key early test of the new U.S. administration’s approach to Iran. The document reiterates that “President Biden has made clear that if Iran returns to full performance of its JCPOA commitments, the U.S. is prepared to do the same,” using an abbreviation for the 2015 accord that’s all but collapsed under the weight of American sanctions.

Iran has violated key restrictions on uranium enrichment and production capacity since the U.S. under former President Donald Trump left the nuclear accord in May 2018 and reimposed economic penalties. Each government is now demanding the other make the first move toward restoring the pact.

The IAEA reported Tuesday that Iran’s stockpile of uranium had been enriched closer to levels needed for a weapon for the first time in eight years. It also said that Iranian explanations over decades-old uranium traces detected at several sites were inadequate. Tehran has always maintained it’s never sought a bomb.

The proposed censure suggests the U.S. is ratcheting up the pressure. “The world has long known that Iran pursued nuclear weapons in the past,” according to the document. “We also know that Iran retained a vast collection of records from its past nuclear weapons program. Iran must now cooperate fully with the IAEA so we may have assurance that the legacy of Iran’s past nuclear weapons work does not include undeclared nuclear material in Iran today.”

A suggestion that Iran could be providing incomplete information has potentially serious consequences, including another referral to the United Nations Security Council.

The IAEA erupted in rancor the last time the U.S. led an effort to censure Iran, with China lambasting what it saw as U.S. bullying under Trump.

While that June measure ultimately passed, it left the body that’s responsible for accounting for gram-levels of nuclear material worldwide badly divided. Russia, India, Pakistan and South Africa were among the countries that joined China in either opposing the measure or abstaining from the vote.

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