Pentagon official Gregg William Bergersen, Chinese citizen Yu Xin Kang and Taiwan-born US citizen Tai Shen Kuo were held for allegedly passing classified information to China, mostly pertaining to US military sales to Taiwan, according to Justice Department officials.

Bergersen, 51, is a weapons systems policy analyst at the Pentagon's Defense Security Cooperation Agency, which implement's the US Defense Department's foreign military sales program.

In another case, former Boeing engineer Dongfan "Greg" Chung, a China-born US citizen, was arrested on charges of stealing and turning over trade secrets also to China, including on the space shuttle used for US human space flight missions.

Aside from the shuttle, Chung, 72, was charged with economic espionage involving secrets on the C-17 military transport plane and the Delta IV rocket while he worked at Boeing and, before that, at US defense contractor Rockwell International.

Both cases had a common objective: "to get a hold of our nation's military secrets," Assistant US Attorney General Kenneth Wainstein told reporters.

"Such espionage networks pose a grave danger to our national security and to our economic position in the world," he said.

They were complete with traditional elements of spy tradecraft, including foreign handlers, payoffs, cut-out couriers, intelligence taskings to an aerospace engineer and a "compromised government employee," he said.

China's foreign secret service was among the "most aggressive" in trying to steal sensitive US military technology and information, Wainstein noted.

Director of National Intelligence Michael McConnell charged recently that Chinese and Russian spies were stalking the United States at levels close to those seen during the tense covert espionage duels of the Cold War.

Kuo, 58, is accused of having worked under the direction of an unnamed Chinese official to obtain classified US defense information from Bergersen, who maintains a "top secret security clearance" at the Pentagon.

Kang, 33, a US permanent resident, was named as a "conduit of information" between Kuo and the Chinese official.

Kuo and Kang, both of New Orleans, Louisiana, both face up to life in prison if convicted for the charge of criminal conspiracy to disclose national defense information to a foreign government.

Bergersen, who resides in Alexandra, Virginia, was charged with disclosing national defense information to unauthorized persons, which could bring up to 10 years in prison.

Chung, 72, who lives in Orange, California, was charged with economic espionage, having allegedly received directives since as early as 1979 from China's aviation industry telling him to collect specific information.

Chung was charged with eight counts of economic espionage -- each of which carries a maximum possible 15 year prison sentence and 500,000 dollar fine -- and six other related charges.

The Justice Department said the Chung case is linked to its investigation into California resident and engineer Chi Mak and members of his family, who were convicted last year for providing US defense articles to China.

"Mr. Chung is accused of stealing restricted technology that had been developed over many years by engineers who were sworn to protect their work product because it represented trade secrets," said US Attorney Thomas O'Brien.

"Disclosure of this information to outside entities like the PRC would compromise our national security," he said.

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