ISIS’ potential acquisition of radioactive material generates a potential scenario in which the Sunni extremist group may try to produce and use a “dirty bomb”.

Over the past two weeks, radioactive material stolen from a facility in Iraq has reinvigorated fears regarding the capacity for ISIS to obtain nuclear compounds. The subsequent revelation that the ISIS-linked perpetrators of the November Paris attacks were also covertly surveilling a high-ranking Belgian nuclear official have only escalated these concerns further.

In assessing these two developments together, the conclusion is substantial: ISIS nuclear espionage in Belgium demonstrates a focused intention to acquire radioactive substances, and the theft in Iraq denotes the ease and proximity of their attainment. Though the materials were recently found abandoned on the side of an Iraqi freeway, the acquisition of nuclear material may be within the capacity of ISIS.

Considering the immense logistic, scientific, and technical barriers to assembling a full-fledged nuclear device, analysts have broadly recognized that ISIS may instead be plotting to craft a “dirty bomb” — a device combining conventional explosives with nuclear materials.

These estimations, however, raise more questions than are answered, and it is important for such a fear-inducing risk to be wholly represented. How probable really is it for ISIS to develop a “dirty bomb,” and what is the full nature and impact of the impending threat that would follow?

Higher than perceived probability

Due to the relative technical simplicity of a “dirty bomb,” the probability of ISIS launching a radioactive attack depends almost entirely on the acquisition of rare radioactive compounds. With the organization’s nuclear intentions now apparently clear, there are two primary sources from which these high-risk prerequisites could be secured.

In light of the recent developments in Iraq and Belgium, the first and most prominent means through which ISIS might seek lucrative nuclear materials is through force or theft. With nuclear substances found in radiological devices, laboratories, and nuclear power plants around the world, the risk is present both within its base of operations in the Middle East and North Africa as well as in any number of countries where ISIS members are active.

The terrorist group has already been reported as having seized roughly 40 kg of uranium compounds from an Iraqi university in 2014, though the United Nations later categorized the materials as “low grade” and insignificant. In fact, the notion that ISIS operatives may have sought radioactive materials from Belgium suggests that local sources — namely Syria and Iraq — have been deemed less adequate for constructing an effective radiological explosive. This is likely a result of neither country possessing the larger sums of radioactive materials seen in countries with nuclear power plants, combined with the consistently poor nuclear security in Belgium.

Recognizing ISIS capabilities and reach, the potential exists for the organization to seek highly radioactive materials from nuclear power plants through the coercion of nuclear officials, as appears to have been the plan in Belgium. These materials yield a significantly greater risk than those obtained from the medical and industrial devices sought after in Iraq and Syria, but are also more challenging to acquire.

The prospect of combining smaller amounts of radioactive materials seized across ISIS territory ultimately presents the greater probability for a “dirty bomb,” albeit with a lower threat from radiation.

A second means through which ISIS might acquire nuclear materials is through the black market, from which deals involving the sale of nuclear materials to the organization have already been thwarted. Such deals have in the past been contained by the FBI and other intelligence agencies, though they are likely to be continued in practice.

Between these two methods for acquiring radioactive substances, the probability of ISIS detonating some form of “dirty bomb” is high.

A broad range of impacts

With a high risk of ISIS potentially utilizing a radioactive explosive device the question now turns to how impactful such an attack would be.

According to senior Iraqi officials, the recently radioactive stolen and later found materials amounted to approximately ten grams of Iridium-192, a standard supply found within medical and industrial devices utilizing radiography. While the scale of harm is determined by a variety of factors such as grade and half-life, and while the materials were ultimately recovered, the figure helps to provide an overview of the impacts expected from an ISIS “dirty bomb”.

Harm caused by radiation is measured in units called microsieverts. Ten grams of Iridium-192 contains roughly 3,500 curies of radiation, which translates into approximately 1.5 million microsieverts per hour to individuals standing 10 feet away if the material is concentrated in one area unshielded. For perspective, 100,000 microsieverts is the lowest yearly dose linked to increased cancer risk, and 2 million microsieverts results in often fatal radiation poisoning. Thus, the ten grams of Iridium-192 available to ISIS through devices scattered across Iraq and Syria is dangerous within minutes of exposure and potentially deadly over hours.

However, it is important to recognize that an equivalent “dirty bomb” would entail the explosive dispersal of radioactive material over a much broader space, diluting the radiation impact significantly and leaving only minor physical risk outside of the initial blast itself.

Since ISIS is most probable to obtain radioactive materials from devices in Iraq and Syria, the physical impact of a hypothetical ISIS device will likely be low and is prone to being overstated. Should ISIS acquire larger amounts of radioactive matter from the less likely scenarios of the nuclear black market or infiltrations of foreign nuclear plants, the threat from radiation becomes a significant concern.

The most probable risk generated by an ISIS “dirty bomb” is the wide-spread panic that would likely follow. Areas surrounding the detonation would be shut-down for weeks or even months depending on the half-life of the substance used, resulting in severe local economic loses.

Geopolitical tensions may also be escalated, as the complex web of countries involved in Syria, Iraq, and the war against the Islamic State would likely ratchet up military involvement on all sides.

In short, the Islamic State’s intentions to construct a radioactive weapon are a concerning probability. The scope of such a weapon’s physical impact is limited. Given the difficulties of covertly transporting radioactive materials, such an attack is most likely to occur within the proximity of ISIS core territory. But the resources and organization of the terrorist group ensure that the threat is a truly global in nature.