This is a guest post by Frank L. Smith III, lecturer at the University of Sydney and author of the new book, American Biodefense: How Dangerous Ideas About Biological Weapons Shape National Security.

The 2003 Iraq War aimed to stop rogue states from using weapons of mass destruction or giving these weapons to terrorists. Now we face ISIS, a terrorist organization that also claims to be a state. But what about WMD? Last week, Foreign Policy reported the discovery of an ISIS laptop that contained a jihadi fatwa on how “it is permissible to use weapons of mass destruction,” and, far more troubling, instructions on how to use biological weapons. So has the Islamic State become the triple threat that we supposedly invaded Iraq to prevent?

The laptop in question was captured in Syria earlier this year. Its previous owner was a Tunisian-turned-ISIS fighter who studied chemistry and physics at university. Along with a variety of other material on conducting jihad, “the ISIS laptop contains a 19-page document in Arabic on how to develop biological weapons and how to weaponize the bubonic plague from infected animals.”

This is clearly not good news. ISIS is bad enough already, and an Islamic State armed with biological weapons would be even worse. As the document on this laptop suggests, “the advantage of biological weapons is that they do not cost a lot of money, while the human casualties can be huge.” Plague is certainly contagious enough and infamous enough to fuel fear. Moreover, the spectre of WMD often creates considerable confusion to the detriment of sound policy – confusion that I explain in my book about “WMD” and other dangerously inaccurate stereotypes.

That being said, the threat of bioterrorism is not new and a position paper does not mean that ISIS actually has biological weapons. Building biological weapons requires a lot of skill, including tacit knowledge that cannot be conveyed on paper. The technical challenges are considerable, though certainly not insurmountable, and neither chemistry nor physics equate to biological expertise.

It’s also worth noting that plague isn’t a doomsday device. Unlike the natural outbreak of Ebola virus, plague can be treated with antibiotics. Given these drugs and modern sanitation, the Black Death isn’t what it once was. The route of exposure is still important: respiratory or pneumonic plague is very dangerous. But without access to the complete text, it’s unclear if creating an aerosol for inhalation is what this document really means by “how to weaponize the bubonic plague.” Unlike anthrax spores, plague is also fragile and so making it into a potent aerosol can be difficult.

In addition, the recovered document reportedly says to “use small grenades with the virus.” But plague is caused by bacteria, not a virus. Reference to “the virus” may therefore be a translation error, a sign that other pathogens are being discussed, or – if we’re lucky – evidence that this document isn’t particularly sophisticated.

Luck is not a strategy, however, and bioterrorism and biological warfare have long been credible threats to the United States. It would be unwise to either inflate the threat of “WMD” in response to this captured laptop or dismiss the danger of biological weapons. Instead, a careful and considered approach to biodefense is probably best. This would include looking for suspicious symptoms, monitoring high value targets, and, more important, having drug stockpiles ready to deploy along with operational plans for how the U.S. and its allies will provide mass casualty care for disease. Credible countermeasures reduce the probability that biological weapons are used and limit the damage in the event that ISIS ever acts on this particular aspiration.