/ Former CIA officer John Kiriakou, left, and his attorney John Hundley, leave federal court in Alexandria, Va., on Jan. 23.

Former CIA officer John Kiriakou, accused of leaking sensitive classified information to reporters, pleaded guilty on Tuesday to revealing the identity of a covert operative.

Kiriakou, who initially pleaded not guilty to five federal charges, pleaded guilty to a single count at a hearing at U.S. District Court in Virginia. Under a plea bargain, he is expected to serve 30 months in prison when he is formally sentenced on Jan. 25. Prosecutors, in return, agreed to ask that the Bureau of Prisons let him serve his time at a minimum security camp in Pennsylvania.

Kiriakou, 48, was accused of furnishing classified secrets to a New York Times reporter -- and lying to the government -- about another CIA officer's role in the capture of Abu Zubaydah, the former high-ranking al-Qaida leader who was waterboarded more than 80 times after his capture.

CIA Director David Petraeus called Kiriakou's guilty plea "an important victory for our agency, for our intelligence community and for our country" in a statement to CIA employees on Tuesday.

"Oaths do matter, and there are indeed consequences for those who believe they are above the laws that protect our fellow officers and enable American intelligence agencies to operate with the requisite degree of secrecy," he said.

The guilty plea closes one of six prosecutions the Obama administration has pursued in an aggressive campaign against alleged leakers of classified information. It also means that some journalists who were questioned about the case will not have to testify at a trial.

His guilty plea came after he lost a key pre-trial ruling. Kiriakou's lawyers had argued unsuccessfully that prosecutors should have to prove that he intended to harm the United States through his alleged leaks.

But U.S. District Judge Leonie Brinkema ruled last week that such a high standard should not apply to Kiriakou, a government employee with top-secret security clearances who knew well the dangers of disclosing classified information.

When he was indicted in April, Kiriakou was charged with one count of disclosing classified information identifying a covert agent, three counts of illegally disclosing national defense information and one count of making false statements. He had faced up to 45 years in prison if convicted on all counts.

Kiriakou, who wrote a book detailing his CIA career, had tried to argue after the charges were filed that he was a victim of vindictive prosecution by government officials who believed he portrayed the CIA negatively, but the judge rejected those arguments as well.

NBC News Pentagon Producer Courntey Kube and the Associated Press and Reuters contributed to this report.

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