Colin H. Kahl writes: For Israelis considering a strike on Iran, [Israel’s 1981 attack on the Iraqi nuclear reactor at] Osirak seems like a model for effective preventive war. After all, [Saddam] Hussein never got the bomb, and if Israel was able to brush back one enemy hell-bent on its destruction, it can do so again. But a closer look at the Osirak episode, drawing on recent academic research and memoirs of individuals involved with Iraq’s program, argues powerfully against an Israeli strike on Iran today.

To begin with, Hussein was not on the brink of a bomb in 1981. By the late 1970s, he thought Iraq should develop nuclear weapons at some point, and he hoped to use the Osirak reactor to further that goal. But new evidence suggests that Hussein had not decided to launch a full-fledged weapons program prior to the Israeli strike. According to Norwegian scholar Målfrid Braut-Hegghammer, a leading authority on the Iraqi program, “on the eve of the attack on Osirak . . . Iraq’s pursuit of a nuclear weapons capability was both directionless and disorganized.”

Moreover, as Emory University political scientist Dan Reiter details in a 2005 study, the Osirak reactor was not well designed to efficiently produce weapons-grade plutonium. If Hussein had decided to use Osirak to develop nuclear weapons and Iraqi scientists somehow evaded detection, it would still have taken several years — perhaps well into the 1990s — to produce enough plutonium for a single bomb. And even with sufficient fissile material, Iraq would have had to design and construct the weapon itself, a process that hadn’t started before Israel attacked.

The risks of a near-term Iraqi breakthrough were further undercut by the presence of French technicians at Osirak, as well as regular inspections by the International Atomic Energy Agency. As a result, any significant diversion of highly enriched uranium fuel or attempts to produce fissionable plutonium would probably have been detected.

By demonstrating Iraq’s vulnerability, the attack on Osirak actually increased Hussein’s determination to develop a nuclear deterrent and provided Iraq’s scientists an opportunity to better organize the program. The Iraqi leader devoted significantly more resources toward pursuing nuclear weapons after the Israeli assault. As Reiter notes, “the Iraqi nuclear program increased from a program of 400 scientists and $400 million to one of 7,000 scientists and $10 billion.”

Iraq’s nuclear efforts also went underground. Hussein allowed the IAEA to verify Osirak’s destruction, but then he shifted from a plutonium strategy to a more dispersed and ambitious uranium-enrichment strategy. This approach relied on undeclared sites, away from the prying eyes of inspectors, and aimed to develop local technology and expertise to reduce the reliance on foreign suppliers of sensitive technologies. When inspectors finally gained access after the 1991 Persian Gulf War, they were shocked by the extent of Iraq’s nuclear infrastructure and how close Hussein had gotten to a bomb.