US federal prosecutors have charged two Chinese nationals with smuggling a toxic fungus into the United States, which authorities claim could be turned into a “potential agroterrorism weapon”.
The charges against Jian Yunqing, 33, and Liu Zunyong, 34, two researchers from China, were unsealed by the US Attorney’s Office for the Eastern District of Michigan on Tuesday. The pair face additional charges of conspiracy, visa fraud and providing false statements to investigators.
Prosecutors allege that Liu smuggled the fungus, called Fusarium graminearum, into the US so he could carry out research at a University of Michigan laboratory where his girlfriend, Jian, worked.
Fusarium graminearum causes “head blight”, a disease in crops like wheat, barley, maize and rice, and is “responsible for billions of dollars in economic losses worldwide each year”, according to the charges.
The pathogen also poses a danger to humans and livestock, and can cause “vomiting, liver damage, and reproductive defects”.
The investigation was carried out by US Customs and Border Protection and the FBI, whose mandate includes investigating foreign and economic espionage as well as counterterrorism.
Jian was earlier arrested by the FBI and is due to appear in federal court this week, where her ties to the Chinese government are also under scrutiny at a time of increased paranoia within the US government about possible Chinese infiltration.
Jian allegedly received funding from the Chinese government to carry out research on the same toxic fungus in China, according to the charges.
The Associated Press news agency, citing the FBI, said that Liu was sent back to China from Detroit in July 2024 after airport customs authorities found the fungus in his backpack. He later admitted to bringing the material into the US to carry out research at the University of Michigan, where he had previously worked alongside his girlfriend, the AP said.
During their investigation, the FBI found an article on Liu’s phone titled “Plant-Pathogen Warfare under Changing Climate Conditions”. Messages on the couple’s phones also indicated that Jian was aware of the smuggling scheme, and later lied to investigators about her knowledge.
It is unlikely that Liu will face extradition as the US does not have an extradition treaty with China.
FBI director Kash Patel claimed on X that China was “working around the clock to deploy operatives and researchers to infiltrate American institutions and target our food supply, which would have grave consequences”.
New… I can confirm that the FBI arrested a Chinese national within the United States who allegedly smuggled a dangerous biological pathogen into the country.
The individual, Yunqing Jian, is alleged to have smuggled a dangerous fungus called “Fusarium graminearum,” which is an…
— FBI Director Kash Patel (@FBIDirectorKash) June 3, 2025
The Chinese Embassy in Washington, DC did not immediately respond to a request for comment.
The University of Michigan on Tuesday issued a brief statement condemning “any actions that seek to cause harm, threaten national security, or undermine the university’s critical public mission”.
The case comes just a week after US Secretary of State Marco Rubio pledged to start “aggressively” revoking the visas of Chinese students in the US on national security grounds.
Targeted students include Chinese nationals with ties to the Chinese Communist Party (CCP), an institution that counts about 100 million members. While some Chinese may join for ideological reasons, membership in the CCP comes with perks like access to better jobs and educational opportunities.
It is not uncommon for students from elite backgrounds, like those studying in the US, to also be members of the CCP.
China’s Ministry of Foreign Affairs has previously pledged to “firmly safeguard the legitimate rights and interests” of its students studying overseas following news of the visa crackdown.