Iran is dramatically ramping up production of enriched uranium in the wake of the Trump administration’s decision to abandon the 2015 nuclear deal, the U.N. nuclear watchdog confirmed Tuesday while also criticizing Tehran for blocking access to possible nuclear-related sites.

Inspectors from the International Atomic Energy Agency reported a near-tripling of Iran’s stockpile of low-enriched uranium just since November, with total holdings more than three times the 300-kilogram limit set by the nuclear accord. Iran also substantially increased the number of machines it is using to enrich uranium, the agency said, allowing it to make more of the nuclear fuel faster.

The confidential report provided to member states and obtained by The Washington Post is the first since Iran announced it would no longer adhere to any of the nuclear pact’s restrictions on uranium fuel production, in a protest of the Trump administration’s decision to walk away from the deal. Iran has declined to formally pull out of the agreement, known as the Joint Comprehensive Plan of Action, in which it had to sharply curtail its nuclear activities and submit to intrusive inspections in exchange for relief from economic sanctions.