A Chinese national has been charged with spying on US citizens in an attempt to recruit scientists and engineers.
Ji Chaoqun is alleged to have been providing Chinese intelligence with information about eight US citizens, some of whom were defence contractors.
He was charged with one count of knowingly acting as an agent of a foreign government, without prior notification to the US attorney general.
Ji appeared in court on Tuesday with an interpreter. When asked if he knew his rights, he answered "I understand" in English.
He faces up to 10 years in prison if he is convicted. He was held in custody after the hearing.
It is believed Ji first arrived in Chicago five years ago on a student visa to study electrical engineering.
The court affidavit says Ji was working at the direction of a "high-level intelligence officer" in China's Ministry of State Security, which "handles civilian intelligence collection and is responsible for counter-intelligence and foreign intelligence, as well as political security".
Ji is said to have admitted to his work after one of his handlers was arrested earlier this year.
He is said to have told undercover agents: "They just wanted me to purchase some documents on their behalf. Their reason was just because it was inconvenient for them to make payments from China."
After a warrant was issued to search Ji's email account in March 2018, investigators found he had emailed background reports on eight US individuals generated by three different background report companies.
He sent the documents in an email with a subject line about midterm quiz questions.
The companies only accept payments from US credit cards and for US customers.
In a statement, the US Department of Justice said: "In 2016, Ji enlisted in the US army reserves as an E4 specialist under the Military Accessions Vital to the National Interest (MAVNI) programme, which authorises the US armed forces to recruit certain legal aliens whose skills are considered vital to the national interest.
"In his application to participate in the MAVNI program, Ji specifically denied having had contact with a foreign government within the past seven years, the complaint states.
"In a subsequent interview with a US army officer, Ji again failed to disclose his relationship and contacts with the intelligence officer, the charge alleges."
The eight people Ji is alleged to have been spying on are naturalised US citizens who were born in Taiwan or China.
Court documents say investigators trawled Ji's phone records and found dozens of texts between him and two intelligence officers, including arrangements to meet up.
Relations between the US and China are already strained because of Donald Trump's approach to tariffs.
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On Monday, the US president imposed extra tariffs on $200bn (£152bn) worth of Chinese goods, mostly technology-related products. China then announced a series of retaliatory tariffs on $60bn (£45.6bn) of US imports.
It follows a lengthy row between the president and China over the America's trade deficit with the nation.