On the day ISIS overran the Iraqi city of Mosul in 2014, it laid claim to one of the greatest weapons bonanzas ever to fall to a terrorist group: a large metropolis dotted with military bases and garrisons stocked with guns, bombs, rockets and even battle tanks.
But the most fearsome weapon in Mosul on that day was never used by the terrorists. Only now is it becoming clear what happened to it.
Locked away in a storage room on a Mosul college campus were two caches of cobalt-60, a metallic substance with lethally high levels of radiation. When contained within the heavy shielding of a radiotherapy machine, cobalt-60 is used to kill cancer cells. In terrorists’ hands, it is the core ingredient of a “dirty bomb,” a weapon that could be used to spread radiation and panic.
Western intelligence agencies were aware of the cobalt and watched anxiously for three years for signs that the militants might try to use it. Those concerns intensified in late 2014 when ISIS officials boasted of obtaining radioactive material, and again early last year when the terrorists took over laboratories at the same Mosul college campus with the apparent aim of building new kinds of weapons.
In Washington, independent nuclear experts drafted papers and ran calculations about the potency of the cobalt and the extent of the damage it could do. The details were kept under wraps on the chance that Mosul’s occupiers might not be fully aware of what they had.
Iraqi military commanders were apprised of the potential threat as they battled ISIS militants block by block through the sprawling complex where the cobalt was last seen. Finally, earlier this year, government officials entered the bullet-pocked campus building and peered into the storage room where the cobalt machines were kept.
They were still there, exactly as they were when ISIS seized the campus in 2014. The cobalt apparently had never been touched.
“They are not that smart,” a relieved health ministry official said of the city’s former occupiers.
Why ISIS failed to take advantage of its windfall is not clear. US officials and nuclear experts speculate that the terrorists may have been stymied by a practical concern: how to dismantle the machines’ thick cladding without exposing themselves to a burst of deadly radiation.
More certain is the fact that the danger has not entirely passed. With dozens of ISIS stragglers still loose in the city, US officials requested that details about the cobalt’s current whereabouts not be revealed.
They also acknowledged that their worries extend far beyond Mosul. Similar equipment exists in hundreds of cities around the world, some of them in conflict zones.
“Nearly every country in the world either has them, or is a transit country” through which high-level radiological equipment passes, said Andrew Bieniawski, a vice president for the Washington-based Nuclear Threat Initiative who once led US government efforts to safeguard such materials.
“This,” he said, “is a global problem.”
The worries began within hours of ISIS’ stunning blitz into Iraq’s second-largest city.
As TV networks showed footage of triumphant terrorists parading through Mosul’s main thoroughfares, intelligence agencies took quiet inventory of the vast array of military and material wealth the militants had suddenly acquired. The list included three Iraqi military bases, each supplied with US-made weapons and vehicles. It also included bank vaults containing hundreds of millions of dollars in hard currency, as well as factories for making munitions and university laboratories for mixing chemicals used in explosives or as precursors for poison gas.
But a far bigger radiological concern was the cobalt. Intelligence agencies knew of the existence in Mosul of at least one powerful radiotherapy machine used for cancer treatment, one that could potentially provide ISIS with a potent terrorist weapon.
Outside experts were becoming aware of the threat as well.
In 2015, the Institute for Science and International Security, a nonprofit organization in Washington that monitors global nuclear threats, began conducting research to answer the basic questions: How many machines were in Mosul? Where were they deployed? And exactly how powerful were they?
The group obtained documents showing that two different medical centers in Mosul had obtained cobalt-60 machines in the 1980s. Other records showed that at least one of the devices was in active use as recently as 2008 and that in the following year Iraqi officials had sought replacement parts, including new cobalt-60 cores, for both.
From the records, the institute’s experts could draw broad conclusions about the cobalt inside the machines. In a draft report written in November 2015, research fellow Sarah Burkhard calculated that the radioactive cores, when new, contained about nine grams of pure cobalt-60 with a potency of more than 10,000 curies — a standard measure of radioactivity. A person standing three feet from the unshielded core would receive a fatal dose of radiation in less than three minutes.
The institute quietly shared its findings with US intelligence and military officials in late 2015 but declined to publish its report, fearing that ISIS occupiers would benefit from the information. The Washington Post became aware of the report last year but agreed to a US government request to delay writing about it until after Mosul’s liberation.