FBI Arrests Chinese National in Spy Ring Investigation : Espionage: He allegedly unsuccessfully sought to steal secrets about a Navy torpedo and a jet engine. The action ends a 6 1/2-year probe.

The FBI arrested a Chinese national in Charlotte, N.C., who is suspected of taking part in a spy ring that unsuccessfully sought secrets on an advanced Navy torpedo and a jet engine, the bureau announced Saturday.

The arrest of Yen Men Kao by FBI and immigration agents on Friday wrapped up a 6 1/2-year investigation that determined that Kao, 54, and “several other Chinese nationals” conspired to steal and export classified and embargoed high-technology items, officials said. Kao was charged with violating U.S. immigration laws.

The announcement did not specify whether the alleged conspirators were working for Chinese intelligence or whether any others were thought to be still in the United States. The Federal Bureau of Investigation declined to elaborate, and officials at China’s embassy here did not return calls for comment.

The attempted espionage targeted the Navy’s MK 48 Advanced Capability Torpedo and the F 404-400 General Electric jet engine used to power the Navy’s F/A-18 Hornet fighter, the FBI said.

“This protracted investigation yielded a significant amount of counterintelligence information,” including the identities of numerous suspected intelligence operatives and commercial entities involved in Kao’s alleged attempts to illegally acquire U.S. technology, said Joseph P. Schulte Jr., special agent in charge of the FBI’s North Carolina offices.

The decision to charge Kao with immigration violations only and to seek to deport him could indicate that the government wants to return to a policy of downplaying espionage involving allies or nations with which the United States wants to avoid strained relations. The Administration of former President Jimmy Carter ended the general policy of deporting rather than prosecuting foreigners caught in espionage activities.

But a government official familiar with the matter said the handling of the case matched the degree of threat presented by the alleged espionage efforts, rather than any diplomatic considerations.

Kao was charged with violating a section of the Immigration and Nationality Act that provides for deporting a foreigner involved in any espionage or sabotage activity or seeking to illegally acquire U.S. technology.