US General Cartwright has been indicted for espionage

Washington (CNN) -- The former vice chairman of the U.S. Joint Chiefs of Staff is under investigation by the Justice Department regarding material in a book by David Sanger, a correspondent for The New York Times, a source directly familiar with the situation said Thursday.

The source could not confirm that the investigation involving retired Marine Gen. James Cartwright is specifically about the Stuxnet computer virus, which Sanger writes about in his recent book "Confront and Conceal: Obama's Secret Wars and Surprising Use of American Power."

NBC News reported Thursday, citing legal sources, that Cartwright has been told he's under investigation for allegedly leaking classified information about Stuxnet, a complex virus that infected computers in Iranian nuclear facilities in 2010.
CNN has been unable to confirm specifics of NBC's report. Officials from the Justice Department, the U.S. Attorney's Office, as well as Cartwright and his lawyer have not commented.

The leak about Stuxnet was one of a series of national security-related leaks last year and had details of how the United States and Israel were behind the cyberattack.
The leaks appeared in the Times, Newsweek and The Associated Press stories. They prompted an FBI investigation and outraged top intelligence lawmakers.

The first story involving leaked information was Sanger's June 2012 piece in the Times about the U.S. role in cyberattacks against Iran's key nuclear enrichment plant at Natanz, revelations that also appear in "Confront and Conceal."

The book describes how a first-term President Barack Obama used "innovative weapons and tools of American power," including an arsenal of cyberweapons, aimed at Iran's nuclear program, according to publisher Random House.

Stuxnet was discovered in July 2010 after it infected the computers used in Iranian nuclear facilities, sabotaging machinery used in uranium enrichment and causing some of Iran's centrifuges to spin out of control.

Cartwright is a former commander of U.S. Strategic Command and became vice chairman of the Joint Chiefs of Staff in 2007. He spent four years there, retiring in 2011.

According to the Washington-based Center for Strategic and International Studies, where he now serves as an expert on defense policy, Cartwright was known at the Pentagon for his technical acumen in cybersecurity, nuclear proliferation and missile defense.

CNN's Peter Bergen contributed to this report.

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