Under a plea agreement, Stephen Kim faces a 13-month prison term for making an unauthorized disclosure of national defense information.
The criminal case stems from a June 2009 news story by Fox News journalist James Rosen. Rosen reported that US intelligence officials warned the president and senior US officials that North Korea would respond to a United Nations Security Council resolution condemning nuclear tests with another nuclear test.
Justice Department officials said Kim's plea concludes the investigation and the prosecution of the case. If a federal judge accepts the plea, Kim will be sentenced on April 2.
The material at issue in the Kim case came from an intelligence report that had been communicated to officials in the intelligence community, including Kim, on the morning that Rosen's story was published, according to an FBI affidavit for a search warrant in the probe.