In the last three years, I have not spent much time wondering whether ISIS has access to radioactive material. I know they have had access, because I had a hand in getting it to them.

In 2005, while working for an air cargo company in Mosul, I delivered a large wooden box, marked for consignment to the University of Mosul. To fly it in, we needed a special plane, an Antonov-12, whose cargo hold was cavernous compared to our usual 727s and DC-8s. The box contained, according to its air waybill, radiological imaging equipment for the university’s teaching hospital. The next day, workers from the hospital met me at my office, and I gently forklifted the crate into their truck. The load seemed off-balance, and I winced when I heard a corner of the box splinter as we strapped it down. But they drove away, and unless that million-dollar piece of medical equipment fell off the back of the truck and ended up strewn across the road, it probably made it safely to the hospital, where it was captured by ISIS nine years later.

ISIS controlled that hospital for three years, and according to a report by Joby Warrick and Loveday Morris in The Washington Post, they left its most dangerous radioactive material, a stash of cobalt-60, undisturbed. Used therapeutically, cobalt-60 burns away tumors. When blown to smithereens, however—perhaps in a populated area—it can poison and kill people and contaminate the surroundings, as the dirty ingredient in a “dirty bomb.” No dirty bomb has ever been used. Warrick and Morris suggest that ISIS refrained from weaponizing their cobalt-60 because they either didn’t know what they had, or doubted their ability to experiment with it without killing themselves in the process.

We have plenty of reason to be confident that if ISIS could reliably and easily make a dirty bomb, they would do so. In 2003, the Saudi jihadist Nasir bin Hammad al-Fahd issued a religious ruling, now famous, that justified use of nuclear and radiological weapons against infidels. Classical Islamic law limits armies from laying absolute waste to their enemies’ land and people. Poisoning wells, devastating crops, and salting the earth are forbidden except in exceptional circumstances. Luckily for a nuclear-armed jihadi, Fahd wrote, we live in precisely such circumstances. A WMD strike would serve as a lump-sum repayment for the countless bombs directed at Muslims—and it might in fact be the only way Muslims could preserve themselves from domination by nonbelievers. Two years ago, according to reports, Fahd pledged allegiance to the Islamic State from his jail cell in Saudi Arabia.

If they did know what they had, I think they were wise to leave it warehoused away, like the hazardous cargo at the end of The Raiders of the Lost Ark. Radiological weapons take training to handle safely. Three minutes in a room with unshielded cobalt-60 will kill you. Try to synthesize nerve gas, and you’re likely to be your own first victim. It’s not clear it would have been a good use of their top talent to spend weeks or months wearing lead pajamas and poking gingerly at a container of cobalt.

Moreover, conventional weapons have worked beautifully for the Islamic State. The Kalashnikov is the spring-loaded mousetrap of the arms industry, highly resistant to improvement. And although the Islamic State has innovated in the field of weaponry—witness their remarkable industry in building suicide car-bombs and armed drones—they have also, in a way, pruned back their imagination to return to simpler forms of brutality. Al-Qaeda operatives never ceased daydreaming about diverse plots and targets: bombing gas stations; crop-dusting cities with napalm; snipping suspension cables on the Brooklyn Bridge; sinking oil tankers; and many other plots that we never heard about. The Islamic State has an R & D team as well, but it sometimes seems that its first observation was that these imaginative plots tended to happen only in the plotters’ imaginations. The simple ones—stabbing random people, or setting off bombs, or driving a truck through a crowd, or blocking exits at a concert and machine-gunning everyone in sight—frequently come to fruition, and kill more people than the daydreamers’ plots would have, even if successfully pulled off.

The most creative terrorist plots (think September 11 as the epitome of creativity) are not necessarily the most effective. The Islamic State realized this, and adapted. A dozen stabbings collectively generate as much fear as a single successful spectacular attack—or a hundred unsuccessful spectacular attacks. And no one can control access to knives, at least not until the government starts monitoring sales in the cutlery section of Crate and Barrel. By comparison, nuclear and radiological material is much more easily controlled. If any government notices an ISIS cell with access to radioactive or even fissile material, the United States and other governments will almost certainly devote immense resources to making sure it is never used.

Will ISIS nuke us, or render part of a city uninhabitable with a dirty bomb? Yes, if they can. But so far, it isn’t entirely irrational for them not even to have tried.

**Related Video:

https://www.theatlantic.com/international/archive/2017/07/why-hasnt-isis-nuked-us-yet/534738/