How Israel Killed Iran's Top Nuke Scientists

When Israel's attacks on Iran began before dawn on June 13, explosions shattered the homes of some of Iran's top scientists, killing nine people who had worked for decades on Tehran's nuclear program.

- Laurence Norman & Dov Lieber

All nine were killed in near-simultaneous attacks to prevent them from going into hiding, according to people familiar with the attacks.

Eleven days later, hours before a cease-fire brokered by the U.S. and Qatar took effect Wednesday, an attack in northern Iran killed another scientist, Sayyed Seddighi Saber, according to Israeli and Iranian state media. He was sanctioned just weeks ago by the U.S. for his nuclear weapons-related work.

The attack on the scientists was considered so fantastical by even its planners that it was called "Operation Narnia," after the fictional C.S. Lewis series.

The killings were the culmination of 15 years of efforts to wipe out one of Iran's most prized assets—the top cadre of scientists who worked on a secret nuclear-weapons-related program that Iran had pursued at least until 2003. Israel has closely tracked the scientists ever since.

While the U.S. and Israel are trying to assess the extent of damage done by their strikes on Iran's main nuclear sites, Israeli Prime Minister Benjamin Netanyahu has claimed the killings have pushed back Iran's nuclear program by years.

Former officials and experts say the attacks against the scientists delivered a powerful blow against Iran's ability to race for the bomb in the aftermath of the conflict. Most of the people killed, a total of at least 11 by the time a cease-fire took effect Wednesday, had hands-on experience in testing and building components of a warhead, like the detonation systems, high explosives and the neutron sources that trigger the chain reaction.

"It's one thing to lose that expertise slowly over time, especially if you are not trying to actually build a bomb. You have time to replace them," said Eric Brewer, who was U.S. national security director for counterproliferation. "But if you're in the middle of trying to build a bomb or if you see that as a potential near-term option, then it's going to have a bigger impact."