WASHINGTON — A Defense Department analyst and a former engineer for Boeing Co. were charged Monday in separate spy cases for allegedly selling military secrets to the Chinese government, the Justice Department said.

Additionally, two Chinese immigrants accused of working with the defense analyst were arrested after an FBI raid Monday morning on a New Orleans home where one of them lived.

The two cases — based in Alexandria, Va., and Los Angeles — have no connection, and investigators said it was merely a coincidence that charges would be brought against both on the same day.

The cases show "that foreign spying remains a serious threat in the post-Cold War world," Assistant Attorney General Kenneth Wainstein said in a prepared statement.

The Justice Department was to discuss the charges at an afternoon news conference in Washington.

Prosecutors said defense analyst Gregg W. Bergersen, 51, of Alexandria, Va., sold classified defense information to a New Orleans businessman for an undisclosed amount of money. In return, the businessman, identified as Tai Kuo, 58, a naturalized U.S. citizen, forwarded the information to the Chinese government.

Much of the data concerned U.S. military sales to Taiwan, prosecutors said. A third alleged conspirator in the case, Chinese national Yu Xin Kang, 33, served as the go-between for Kuo and the People's Republic of China, according to prosecutors.

Kuo and Bergersen, a weapons systems policy analyst at the Defense Security Cooperation Agency in Arlington, Va., were set to appear in federal court in Alexandria on Monday. Kang was to appear in New Orleans.

In Los Angeles, meanwhile, former Boeing engineer Dongfan "Greg" Chung, 72, was arrested on charges of working as an unregistered agent for the Chinese government who stole trade secrets from the defense contractor. The stolen data largely focused on aerospace programs, including the Space Shuttle, prosecutors said.

Chung, a naturalized U.S. citizen, was indicted last week on espionage, conspiracy and obstructing justices charges that were unsealed Monday. He has been the subject of an FBI investigation for nearly a year as part of an inquiry into another Chinese-born engineer who was convicted in 2007 of stealing military data for the Chinese government.

As early as 1979, prosecutors said, Chinese officials were tasking Chung to collect data on U.S. aviation, including the Space Shuttle and various military and civilian aircraft. At one point, Chung responded in a letter that he wanted to "contribute to the motherland," according to the Justice Department.

Over an 18 year span, Chung traveled to China many times to deliver lectures on the Space Shuttle and other programs, and he allegedly met with Chinese government officials there to discuss how to transfer U.S. data.

Chung, who has a security clearance, worked for contractor Rockwell International from 1973 until 1996, when the company's defense and space firm was acquired by Boeing. He retired from Boeing in 2002 but returned the next year as a contractor. He ultimately left Boeing in 2006.