A former counterterrorism agent at the F.B.I. who gave classified documents to the news media in an effort to reveal how the bureau treated minority communities pleaded guilty on Tuesday to the unauthorized disclosure and retention of national defense information.

It is the most recent prosecution in a growing series of leak cases being pursued by the Justice Department, which has significantly increased its focus on such investigations since President Trump took office. However, the actions of the agent, Terry J. Albury, largely predate Mr. Trump’s presidency.

As a field agent in the Federal Bureau of Investigation’s Minneapolis office, Mr. Albury provided a reporter with two documents between February 2016 and Jan. 31, 2017, according to the charges against him. The first document, dated Aug. 17, 2011, described how the bureau evaluated confidential sources; the second, which was undated, concerned “threats posed by certain individuals from a particular Middle Eastern country.” Mr. Albury also possessed, without authorization, “a document relating to the use of an online platform for recruitment by a specific terrorist group.”

“Mr. Albury was entrusted by the F.B.I. with a security clearance, which included a responsibility to protect classified national defense information,” Bill Priestap, assistant director of the bureau’s Counterintelligence Division, said in a statement on Tuesday. “Instead, he knowingly disclosed that material to someone not authorized to receive it.”