At least 14 nuclear scientists are believed to be among those killed in Israel’s Operation Rising Lion, launched on June 13, 2025, ostensibly to destroy or degrade Iran’s nuclear program and military capabilities.
Deliberately targeting scientists in this way aims to disrupt Iran’s knowledge base and continuity in nuclear expertise. Among those assassinated were Mohammad Mehdi Tehranchi, a theoretical physicist and head of Iran’s Islamic Azad University, and Fereydoun Abbasi-Davani, a nuclear engineer who led Iran’s Atomic Energy Organization.
Collectively, these experts in physics and engineering were potential successors to Mohsen Fakhrizadeh, widely regarded as the architect of the Iranian nuclear program, who was assassinated in a November 2020 attack many blame on Israel.
As two political scientists writing a book about state targeting of scientists as a counterproliferation tool, we understand well that nuclear scientists have been targeted since the nuclear age began. We have gathered data on nearly 100 instances of what we call “scientist targeting” from 1944 through 2025.
The most recent assassination campaign against Iranian scientists is different from many of the earlier episodes in a few key ways. Israel’s recent attack targeted multiple nuclear experts and took place simultaneously with military force to destroy Iran’s nuclear facilities, air defenses and energy infrastructure. Also, unlike previous covert operations, Israel immediately claimed responsibility for the assassinations.
But our research indicates that targeting scientists may not be effective for counterproliferation. While removing individual expertise may delay nuclear acquisition, targeting alone is unlikely to destroy a program outright and could even increase a country’s desire for nuclear weapons. Further, targeting scientists may trigger blowback given concerns regarding legality and morality.
A policy with a long history
Targeting nuclear scientists began during World War II when Allied and Soviet forces raced to capture Nazi scientists, degrade Adolf Hitler’s ability to build a nuclear bomb and use their expertise to advance the U.S. and Soviet nuclear programs.
In our data set, we classified “targeting” as cases in which scientists were captured, threatened, injured or killed as nations tried to prevent adversaries from acquiring weapons of mass destruction. Over time, at least four countries have targeted scientists working on nine national nuclear programs.
The United States and Israel have allegedly carried out the most attacks on nuclear scientists. But the United Kingdom and Soviet Union have also been behind such attacks.
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