Retired Marine Gen. James Cartwright arrives at US District Court in Washington, Monday, Oct. 17, 2016. Cartwright has been charged with making false statements during a federal investigation into a leak of classified information, the Justice Department announced. (AP Photo/Pablo Martinez Monsivais)

WASHINGTON - A former vice chairman of the Joint Chiefs of Staff pleaded guilty Monday to making false statements during an investigation into a leak of classified information about a covert cyberattack on Iran's nuclear facilities.

Retired Marine Gen. James Cartwright entered the plea at a hearing before U.S. District Judge Richard Leon, convened just a few hours after the Justice Department announced the charges.

The plea ends a Justice Department investigation that began after the 2012 leak to reporters of information about use of a computer virus called Stuxnet that disabled equipment the Iranians were using to enrich uranium.

The offence carries a maximum of five years in prison, but under a plea agreement, the government is recommending a sentence in the range of zero to six months. Cartwright is scheduled to be sentenced on January 17, and it will be up to Leon to decide the sentence.

Cartwright, 67, falsely told investigators that he did not provide or confirm classified information contained in a news article and in a book by New York Times journalist David Sanger, according to charging documents unsealed by prosecutors.

Neither the book nor the classified subject is identified in court papers. But Sanger wrote in his 2012 book "Confront and Conceal" about the classified operation to attack Iran's nuclear facilities.

The charging documents also say Cartwright misled prosecutors about classified information shared with another journalist, Daniel Klaidman.

Wearing a dark suit, Cartwright stood with his attorney and answered a series of procedural questions from the judge.

"You're pleading guilty because you are in fact guilty, is that right?" Leon asked.

"Yes, sir," Cartwright said.

In a written statement released to reporters after the hearing, Cartwright stressed that he was not the initial source of the leak about Stuxnet but spoke to reporters about material they already knew.

"It was wrong for me to mislead the FBI on Nov. 2, 2012, and I accept full responsibility for this," Cartwright said. He added that his only goal in talking to reporters was "to protect American interests and lives."

Cartwright's attorney, Gregory Craig, said in a statement that his client had spent "his whole life putting the national interest."

"That's why he talked to the reporters in the first place — to protect American interests and lives in a story they had already written," the statement said. "In his conversations with these two reporters, General Cartwright was engaged in a well-known and understood practice of attempting to save national secrets, not disclosing classified information."

The plea agreement said that between January and June of 2012, Cartwright "provided and confirmed classified information" to Sanger. Cartwright also confirmed classified information in February 2012 to Klaidman that was included in an article for Newsweek magazine, the agreement said.

U.S. Attorney Rod Rosenstein of Maryland declined to comment after the hearing.

In a statement Monday, the Times said it would not discuss the sourcing of any information published in the newspaper or by Sanger.

"We are disappointed that the Justice Department has gone forward with the leak investigation that led to today's guilty plea by General Cartwright," the Times said. "These investigations send a chilling message to all government employees that they should not speak to reporters. The inevitable result is that the American public is deprived of information that it needs to know."

Cartwright was vice chairman of the Joint Chiefs of Staff from 2007 until 2011 and was considered a key adviser to President Barack Obama. A former fighter pilot, the Marine general was known for his expertise in the more highly technical areas of cyberwarfare and America's nuclear enterprise.

The New York Times reported in 2012 that Cartwright was a crucial player in the cyber operation called Olympic Games, started under President George W. Bush.

The Times had said that Obama ordered the cyberattacks sped up, and in 2010 an attack using Stuxnet temporarily disabled 1,000 centrifuges that the Iranians were using to enrich uranium.

Iran has publicly blamed the United States and Israel for the computer virus, but neither country has officially acknowledged a role in the attack.

Congressional leaders had called for a criminal investigation into who leaked the information, and some Republicans said senior administrational officials had disclosed the details of the cyber operation to bolster the president's national security credentials during the 2012 campaign. Obama said he had zero tolerance for such leaks.

The Justice Department's investigation into the disclosure of classified information was one of several national-security leak probes conducted during the Obama administration, including ones involving The Associated Press and Fox News.

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Associated Press writer Lolita C. Baldor contributed to this report.

News from © The Associated Press, 2016