A retired U.S. Marine general who at one time was the nation’s second highest-ranking military officer, pleaded guilty Monday to charges that he lied to investigators about leaking classified information.

General James Cartwright, a retired 4-star general, is a former vice chairman of the Joint Chiefs of Staff.

Retired US General Pleads Guilty in Classified Leak Case

Investigators wanted to know if he was the source of the leak to journalists about a computer virus the U.S. and Israel used to disrupt Iran’s nuclear program.

Retired US General Pleads Guilty in Classified Leak Case

A computer virus called Stuxnet caused Iranian centrifuges enriching uranium to spin out of control in 2010, possibly setting back Iran’s efforts to build a nuclear bomb.

Retired US General Pleads Guilty in Classified Leak Case

The information was spelled out in the book by reporter David Sanger.

Cartwright could face up to five years in prison, but reports say his lawyer and government prosecutors have agreed on a six-month sentence.