Iran Maintains Steady Expansion of Nuclear Program

Iran continued to expand its nuclear program, including its stockpile of near-weapons-grade enriched uranium in recent months, although it hasn’t accelerated the pace of its production of nuclear fuel amid the current turmoil in the Middle East.

In its confidential quarterly report circulated to member states, the United Nations nuclear agency also said Tehran has largely refused to cooperate on several outstanding disputes, including the country’s withdrawal of permission for several European inspectors to continue working there.

Wednesday’s International Atomic Energy Agency report showed that while Iran has slowed its accumulation of 60%-enriched uranium since the start of summer, it continues to build up large amounts of material that could be used to fuel nuclear weapons.

Iran added 6.7 kilograms of 60% enriched uranium, taking its stockpile to 128.3 kilograms in the 2 ½ months to Oct. 28, the agency reported. That is enough material—once refined to weapons-grade uranium at 90% purity—to fuel about three nuclear weapons. Iran is the only state without nuclear weapons to produce 60% enriched uranium.

U.S. officials have said it would likely take Iran less than two weeks to produce enough weapons-grade material for a weapon. However, they also have said they believe Tehran hasn’t completed research on building an atomic bomb.

Additionally, Iran has more than half a ton of 20% enriched uranium, which experts say would take several weeks to convert into 90% weapons-grade fuel, potentially allowing Tehran to field a number of nuclear weapons in a short period.

Iran insists its nuclear program is for entirely peaceful civilian programs and that it would never develop nuclear weapons.

The IAEA’s estimates of Iran’s nuclear fuel stockpile were made on Oct. 28, three weeks after the Hamas attack on Israel which killed 1,200 people and unleashed a massive Israeli military offensive in Gaza.

A person close to the agency said Iran had accumulated 60% nuclear fuel at a roughly steady pace of three kilograms a month throughout the latest period, indicating there was no sudden surge in Iran’s nuclear program after Oct. 7.

The agency also reported that during the period Iran didn’t start operating any new centrifuge cascades, machines that spin enriched uranium into higher levels of purity.

Israel has been at the forefront of efforts to stop Iran from developing a nuclear weapon, including killing Iranian scientists involved in such research, attacking some Iranian nuclear facilities and pushing the international community to keep pressure on Tehran.

In the wake of the Oct. 7 attack, Western countries are concerned that the Israel-Hamas war could spiral into a regional conflict involving Iran, with Iran’s proxy forces throughout the region attacking Israeli and U.S. forces. Tehran has long sent weapons and funding to Hamas and openly celebrated the Oct. 7 attack on Israel.

Earlier this year, the U.S. and Iran attempted to de-escalate tensions, including over Iran’s nuclear program. However the U.S. canceled indirect talks with Iran due last month in Oman following the Hamas attack. There has been no sign so far of reviving them.

That leaves Iran effectively as a threshold nuclear state with no clear diplomatic or other plan to defuse the threat. President Biden, like his predecessors, has pledged to prevent the country from obtaining a nuclear weapon.

Meanwhile, Iran has stonewalled for years an investigation by the U.N. nuclear agency into unexplained traces of enriched uranium found in the country.

Tehran has removed agency cameras at Iranian nuclear-related facilities, preventing it from developing a clear picture of the full scope of Iran’s nuclear program.

Ahead of Wednesday’s report, Tehran refused to allow back eight of the IAEA’s most experienced inspectors whom it had recently banned from working there.

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