Where Iran’s Nuclear Program Goes From Here

Deep beneath the Zagros Mountains in central Iran, in a labyrinth of fortified tunnels outside the city of Natanz, centrifuges spun at speeds too fast for the eye to track. The cascade of machines, arranged in long halls and shielded by concrete and steel, have been central to Iran’s most sensitive nuclear work, and, until recently, largely immune to airstrikes. 

But in June, Israeli and U.S. warplanes penetrated Iranian airspace and struck multiple nuclear sites, including underground facilities thought to be untouchable. President Donald Trump said that U.S. bombers had “totally obliterated” three key Iranian nuclear sites. While the extent of the damage remains unclear, initial assessments suggest Iran’s nuclear infrastructure suffered its most significant blow in over a decade. 

The Israeli-U.S. strikes blew up the uneasy nuclear status quo that existed in the Middle East for years while raising a daunting question: What happens if Iran decides that the only true deterrent is to build a bomb?

Read more: A New Middle East Is Unfolding Before Our Eyes

For over a decade, Tehran has operated just below the threshold of nuclear breakout capability. But this spring it abandoned that restraint. The International Atomic Energy Agency reported in May that Iran had accumulated roughly 120 kg of uranium enriched to 60%—­dangerously close to weapons-grade levels of 90%—and enough to build 22 nuclear bombs within five months if further enriched. At the same time, Iran began building a third enrichment hall on top of the two already in use. U.S. officials saw it as a provocation; Israel viewed it as a casus belli.

Israeli and U.S. officials described their military strikes as pre-emptive operations to cripple Iran’s ability to build a nuclear weapon by targeting its main enrichment sites, nuclear scientists, and military officials.

But while the strikes disrupted Iran’s enrichment operations, it retains scientific expertise and stockpiled material, and now possesses a stronger incentive to bury its program even deeper. “If Iran survives the conflict, they could decide that a nuclear weapon is the only way to have deterrence,” says Alex Vatanka, a senior fellow at the Middle East Institute.

Concerns that Iran could attempt a dash for a nuclear weapon played a role in Trump’s decision to target Fordo, a nuclear site buried so deeply in mountains near the city of Qum that only the U.S.’s most powerful bunker-busting bomb—the 30,000-lb. GBU-57—is believed capable of reaching it.

Even before the U.S. bombings, diplomatic efforts to constrain Iran’s program were already on the verge of collapse. “Trying to get to a deal now is infinitely harder than it used to be,” says ­Richard Nephew, who worked on Iran sanctions in the Obama Administration. Others are more hopeful about the outcome of the war. Says Matt Kroenig of the Atlantic Council: “We were on the verge of Iran becoming a nuclear power, and it looks like now we’ve set that threat into the future.”

Update, June 22, 2025:

This story was updated to reflect breaking news.