He committed the ‘crime’ at Boeing and Rockwell during a three-decade career.

Federal Judge Cormac Carney jailed Chung for 188 months at a hearing in Santa Ana, outside of Los Angeles, telling the former engineer it was not possible to "put a price tag" on national security.

The Judge observed that the stiff sentence was intended to send a message to the Chinese government: "Stop sending your spies here."

Chung was found guilty of conspiracy to commit economic espionage, six counts of economic espionage to benefit a foreign country, one count of acting as an agent of the People’s Republic of China and one count of making false statements to the FBI.

A native of China and a naturalized US citizen, Chung held a "secret" security clearance when he worked at Rockwell and Boeing on the space shuttle programme. He retired from the company in 2002. The following year he became a  contractor to the companyand worked in that capacity tilll 2006.

Prosecution said Chung stole Boeing trade secrets relating to the shuttle and the Delta IV rocket. His came came to light while probing another espionage ring in  the sale of sensitive military information to China..