US authorities have charged three Tianjin University professors and three other Chinese citizens with economic espionage, claiming that they stole sensitive US technology to help Chinese universities and government-controlled companies.
One of the six defendants, Professor Hao Zhang, was arrested on Saturday when he arrived at Los Angeles International Airport to speak at a conference. The other suspects are still in China.
Mr Zhang and fellow professor Wei Pang are accused of stealing information about a technology used in smartphones, tablets and GPS devices from their US employers, Skyworks Solutions in Massachusetts and Avago Technologies in Colorado, respectively. The technology also has military applications.
The charges represent the latest sign of the US ratcheting up pressure on China's alleged efforts to spy on US companies and steal their trade secrets through cyber attacks or traditional espionage techniques.
The charges follow the indictment of five Chinese soldiers in 2014 for cyber attacks and economic espionage on US companies. Tuesday's announcement marks the 11th time that prosecutors have levelled economic espionage charges since the related law was passed in 1996.
In 2014, a consultant called Walter Liew was found guilty of 22 counts of economic espionage for stealing information about how DuPont creates a white pigment found in paper and plastic products, to sell to a Chinese company.
In the latest case, the stolen trade secrets include recipes, source code, specifications, presentations, design layouts and other documents, according to the 32-count indictment that was recently unsealed.
An attorney for Mr Zhang did not respond to a request for comment. Skyworks and Avago were not immediately available for comment.
Messrs Zhang and Pang met when they were studying the technology, known as thin-film bulk acoustic resonator or FBAR, as electrical engineering doctoral students in California. Their research was funded by the Defense Advanced Research Projects Agency, or DARPA, which creates technology used by the US military and national security agencies.
FBAR technology, which filters wireless signals to receive and send only what is intended by the user, is also used in military and defence products.
Professors Pang and Zhang, along with others, set up a business plan and pitched Chinese universities on manufacturing FBAR technology in China, the indictment said.
"The defendants leveraged their access to and knowledge of sensitive US technologies to illegally obtain and share US trade secrets with [China] for economic advantage," said Assistant Attorney General John Carlin.
In 2008, officials from Tianjin University, a Chinese Ministry of Education institution, travelled to California to meet Messrs Pang and Zhang, after which the university decided to establish a FBAR fabrication facility in China, prosecutors charged.
The following year, Messrs Pang and Zhang resigned from Avago and Skyworks to become professors at Tianjin University, which formed a joint venture named ROFS Microsystem with the two men and others.
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The stolen trade secrets helped the university establish a state of the art FBAR fabrication facility and to obtain contracts for providing FBARs to commercial and military entities, according to the indictment.
The other Chinese citizens who were indicted include Tianjin professor Jinping Chen, who is also a board director at ROFS Microsystems, and Huisui Zhang, who studied with Messrs Pang and Zhang in California.
Also charged were Chong Zhou, a Tianjin graduate student and a design engineer at ROFS Microsystem, and Zhao Gang, general manager of ROFS Microsystem.
"The conduct reveals a methodical and relentless effort by foreign interests to obtain and exploit sensitive and valuable US technology through the use of individuals operating within the United States," said David Johnson, the FBI Special Agent in Charge.