By Laurence Norman

VIENNA -- Iran has sharply increased its stockpile of highly enriched uranium in recent weeks, according to a confidential United Nations report, as Tehran amasses a critical raw material for atomic weapons.

The increase in Iran's holdings of uranium enriched to 60%, or nearly weapons grade, gives it enough to produce six nuclear weapons.

Iran is now producing enough fissile material in a month for one nuclear weapon, according to the report, which was reviewed by The Wall Street Journal.

Tehran's strides come as the country has indicated an openness to negotiating with the U.S. on limits to its nuclear ambitions. The Trump administration has said it would return to a policy of "maximum pressure" on Iran but that it also wants to negotiate a nuclear deal.

Still, there hasn't been significant direct contact between the two sides since President Trump took office. And Iran has said it won't negotiate directly with Washington while under maximum pressure sanctions.

In an interview Wednesday, the head of the International Atomic Energy Agency, Rafael Grossi, warned that as Iran's nuclear activities advance, "the problem becomes bigger, not smaller," and urged Tehran and Washington to engage. "It is problematic that we are not moving" on talks, he said. "We believe it is necessary to move to action."

The U.N. report said Tehran had amassed around 275 kilograms of 60% highly enriched uranium as of Feb. 8, up from 182 kilograms in late October. That's a 50% jump in 15 weeks. The fuel could be converted to 90% weapons-grade material in days.

Iran, which started producing 60% enriched uranium in 2021, has expanded its production since early December, after facing a censure resolution from Europe and the U.S. at the IAEA.

"The significantly increased production and accumulation of high enriched uranium by Iran, the only nonnuclear weapon state to produce such nuclear material, is of serious concern," the IAEA said in its report.

The head of Iran's atomic agency, Mohammad Eslami, said on Wednesday that Iran was cooperating with IAEA inspectors and that the agency should avoid putting pressure on Iran.

Tehran has made large advances on its nuclear work since Trump was last in office -- when he pulled the U.S. out of the 2015 Iran nuclear deal, which placed strict but temporary restrictions on Iran's nuclear work in exchange for relief from international sanctions.

In 2019, Iran began revving up its nuclear program and officials from the U.S. and elsewhere now believe Tehran could develop some kind of nuclear weapon within a few months. Iran says its nuclear work is for peaceful civilian purposes.

U.S. intelligence reports in December said Iran hadn't made a decision to build a nuclear weapon but there was a growing risk it might do so. U.S. officials have said that Tehran is working on research that could help it build an atomic bomb.

Trump said this month Iran is "too close" to having nuclear weapons. In January, French President Emmanuel Macon said Tehran's program was "close to the point of no return."

The Trump administration has tightened economic pressure on Iran, vowing to slash Tehran's oil sales to China through a stricter implementation of existing sanctions. The Treasury Department this week announced new sanctions on ships and people dealing in Iranian oil.

Iran is at its most vulnerable position in years after its largest regional militia, Hezbollah, was badly damaged in a war with Israel, which in October also took out Tehran's most advanced air-defense systems.

Israel has warned it would take military action if Iran moves toward a bomb. Foreign Minister Gideon Saar told Politico this week that time was running out to pursue a diplomatic path.

European countries have started a process that by October could lead them to reimpose all international sanctions on Iran that were lifted under the 2015 nuclear deal.

Tehran has said if that happens it will quit the international treaty banning countries from pursuing nuclear weapons. The only country to have done that is North Korea, which subsequently built nuclear weapons.

Iran's Supreme Leader, Ayatollah Ali Khamenei, earlier this month publicly warned against negotiations with the U.S., but Iranian officials have told their European counterparts they are keen for talks.

"This confluence of pressure creates a window of opportunity to push for a nuclear and regional deal on Trump's terms," said Michael Singh, former senior director for the Middle East at the U.S. National Security Council. "But that window won't last forever -- Iran is closer than ever to nuclear weapons."

Dan Shapiro, a senior Biden administration Pentagon official who was part of the Iran nuclear negotiation team, said Trump's efforts at rapprochement with Russia could potentially lead to a situation where Washington could get help from Moscow on containing Iran's nuclear work.

Russian Foreign Minister Sergei Lavrov was in Tehran on Tuesday to meet with his Iranian counterpart. He met with U.S. Secretary of State Marco Rubio and Steve Witkoff, Trump's Middle East envoy, in Saudi Arabia last week.

Shapiro said Washington needed to coordinate closely with Europe on the reimposition of sanctions on Iran, saying this could be endangered as "a yawning gulf has opened up between them and Washington on Ukraine."

Write to Laurence Norman at laurence.norman@wsj.com

(END) Dow Jones Newswires

February 26, 2025 13:34 ET (18:34 GMT)

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