Earlier this month, the Justice Department announced charges against Yunqing Jian and Zunyong Liu, two Chinese scientists accused of smuggling a known plant pathogen into the country. Jian, a researcher at the University of Michigan, is alleged to have conspired with her boyfriend, Liu, to sneak the fungus Fusarium graminearum through the Detroit Metropolitan Airport last July. The fungal pathogen is the most common cause of fusarium head blight (FHB), a devastating disease that affects cereal crops such as wheat, barley, rice, and oats.
In announcing the arrests on the social media platform X, FBI Director Kash Patel warned that the case is “a sobering reminder that the CCP [Chinese Communist Party] is working around the clock … to infiltrate American institutions and target our food supply.”
Liu researches Fusarium graminearum at Zhejiang University in China. Upon his arrival in Detroit from Shanghai, U.S. Customs and Border Patrol (CBP) officials discovered four plastic bags containing biological material and a piece of filter paper with a series of circles drawn on it. Liu initially claimed the materials had been planted in his bag by someone else but later admitted that they contained different strains of Fusarium graminearum, which he had planned to research at the University of Michigan lab where Jian worked. According to the criminal complaint, Liu had deliberately concealed the materials because he knew there were restrictions on the importation of the samples.
The FBI has accused Jian and Liu of smuggling “a potential agroterrorism weapon” and argued that their actions posed an “imminent threat to public safety.” At the very least, it’s clear that Jian and Liu knowingly flouted the restrictions on the importation of biological materials—restrictions that protect public health and natural resources by preventing foreign animal diseases and invasive species from entering the United States.
Samples of a pathogen identified by the U.S. Department of Justice as Fusarium graminearum are seen in a criminal complaint by the FBI against Chinese researcher Yunqing Jian and Zunyong Liu on June 2 in this handout image.Via Reuters
Whether Fusarium graminearum could be deployed as a weapon against the U.S. agriculture industry, however, is less apparent. Several experts have questioned whether Fusarium graminearum truly constitutes a national security threat, pointing to the fact that the fungus has been present in the United States for at least 125 years and is not on any plant pathogen watchlist. Nevertheless, proper permits are still required to bring this fungus into the country, and Liu appears to have been aware that he had not taken the requisite steps. Jian and Liu were charged with conspiracy, smuggling goods, false statements, and visa fraud.
Patel’s suggestion that Jian and Liu may have been a part of a state-sponsored plot to infect U.S. crops with the fungus, while so far unproven, is not entirely far-fetched. Indeed, the threat of bioterrorism dates as far back as the 6th century B.C., when the Assyrians reportedly poisoned the wells of their enemies with a fungus that attacked rye plants.
Although most terrorists avoid biological weapons, there are recent exceptions to this rule. In Oregon in 1984, a religious cult deliberately contaminated several restaurant salad bars with salmonella in an attempt to influence the outcome of a local election. Japanese doomsday cult Aum Shinrikyo tried to spray aerosolized botulinum toxin over Tokyo in the 1990s, although the group’s attempts failed. In the wake of 9/11, fears of a second wave of attacks were stoked by the terrifying (though ultimately unrelated) anthrax attacks that occurred just weeks after the World Trade Center fell.
Agroterrorism is a subset of bioterrorism that is defined as a deliberate attack on crops and livestock. It has received comparatively less attention than other forms of terrorism, despite long-held concerns about the vulnerability of the U.S. agricultural system. According to the FBI, when U.S. forces overran al Qaeda sanctuaries in eastern Afghanistan in 2002, they found U.S. agricultural documents and al Qaeda instruction manuals for targeting agriculture.
Although it is possible that al Qaeda intended to carry out an assault on U.S. agriculture or livestock at some point, this type of attack would have been a significant shift away from the group’s usual approach, which emphasized high-profile, mass-casualty terrorism.
For China, on the other hand, an agroterrorism attack fits more neatly into the toolkit of gray-zone tactics that Beijing has increasingly employed to achieve its geopolitical objectives. Chinese state-backed hackers routinely target U.S. industries, government agencies, and private companies to steal classified information; intellectual property; and, in one instance, even COVID-19 relief funds.
The U.S. government has also reported that Chinese nationals have accessed military bases and other sensitive sites as many as 100 times in recent years. U.S. officials have described these incidents as a form of espionage, noting that the intrusions seem designed to test security at military bases and other sensitive sites. Across Asia, gray-zone activities carried out by Chinese nationals have included intentionally cutting Taiwanese undersea cables, violating Japanese airspace, and hacking the systems of an Asian telecommunications company.
None of these hostile actions involve agroterrorism, and a successful attack on the U.S. grain industry would be a departure from China’s typical sabotage attacks and incursions and would represent a dramatic escalation. Such an attack could have devastating effects on U.S. agriculture. FHB reduces crop yield and causes quality losses that have cost the agricultural industry upward of $2.5 billion just from 1998 to 2000. Contaminated grain is more difficult to market, export, and process, and it can contain a variety of mycotoxins that render the grain unfit for either food or animal feed. Plant cultivars strongly resistant to Fusarium graminearum are not yet available, and fungicides are costly for farmers and also relatively ineffective.
Given the length of the grain harvest cycle and the specific weather conditions necessary for rapid FHB spread, the signs of an intentional outbreak would be slow to appear and potentially indistinguishable from a naturally occurring outbreak. Although unusual, this type of attack includes at least some of the qualities China seeks in a gray-zone attack: relatively low-cost, highly disruptive, and deniable.
The charges against Jian and Liu come at a tense moment for U.S.-China relations. Rhetoric on both sides is often hostile, and U.S. tariffs and other trade penalties—as well as China’s response—have disrupted the once-close economic relationship. Tensions between the two countries have been further exacerbated by U.S. President Donald Trump’s crackdown on Chinese students studying in the United States.
It is possible that this investigation is part of the Trump administration’s broader efforts to demonstrate that it can be tough on China. Still, there are certain facts of the case that suggest the concerns around Jian and Liu’s actions may be warranted. Both scientists appear to be legitimate plant pathogen researchers who have each co-authored numerous scientific articles on Fusarium graminearum.
Yet the incident last July was not the first time that the couple had attempted to smuggle biological material into the United States. The criminal complaint filed last week references a previous instant messaging conversation between Jian and Liu in which they allegedly debated how to smuggle seeds through the San Francisco airport.
In another instance detailed in the criminal complaint, Jian directed an individual named Xia Chen to mail her Fusarium graminearum plasmids on filter paper—the same method that Liu used to smuggle his samples into Detroit. Chen allegedly concealed the plasmids within a biostatistics book and shipped it to Jian, although the package that U.S. officials believe was discussed was intercepted by CBP and the samples were destroyed.
Despite this suspicious behavior, it is too early to know whether these smuggling attempts were preparation for a possible agroterrorism attack or simply two quirky scientists breaking the rules to avoid costly permits and time-consuming paperwork. However, it is worth considering the ramifications of an agroterrorism attack and the risks that it would pose to the United States.
While much of the U.S. effort to counter Chinese sabotage and espionage has focused on preventing scientists and academics from making off with intellectual property and sensitive information, there has been less emphasis on trying to prevent bad actors from bringing sensitive materials into the country. The recent Ukrainian deep penetration of Russia for a drone attack demonstrates the kind of damage that can be inflicted on a country when its homeland facilities are vulnerable.
To prevent agroterrorism, the United States should be investing more, not less, money into the study of plant and livestock pathogens. Terrorism aside, these diseases cause global crop losses worth roughly $100 billion to $200 billion each year. As part of this research, there should be an emphasis on forensic techniques that help determine the source of an infection and, to the extent possible, if it has characteristics that might link it to foreign powers.
Similarly, increased efforts to ensure the safety of the food supply are vital for public health as well as national security. Intelligence should be focused on the potential for weaponizing pathogens, including ones far worse than Fusarium graminearum.
More broadly, the United States needs to track, publicize, and organize an allied response to various Chinese gray-zone activities, especially overseas. Perhaps further investigation will reveal that this smuggling attempt has nothing to do with the Chinese government. Still, it seems clear from other incidents around the world that China is engaging in a gray-zone campaign to probe U.S. and allied weaknesses, cause economic harm, and quietly signal that it can and will punish its enemies.