WASHINGTON — Attorney General Jeff Sessions pledged on Friday to rein in government leaks that he said undermine American security, taking an aggressive public stand after being called weak on the matter by President Donald Trump.

The nation’s top law enforcement official cited no current investigations in which disclosures of information had jeopardized the country but said the number of criminal leak probes had dramatically increased in the early months of the Trump administration. Justice Department officials also said they were reviewing guidelines meant to make it difficult for the government to subpoena journalists about their sources, and would not rule out the possibility that a reporter could be prosecuted.

“No one is entitled to surreptitiously fight their battles in the media by revealing sensitive government information,” Sessions said in an announcement that followed a series of news reports this year on the Trump campaign and White House that have relied on classified information. “No government can be effective when its leaders cannot discuss sensitive matters in confidence or to talk freely in confidence with foreign leaders.”

Meanwhile, a White House adviser raised the possibility of lie detector tests for the small number of people in the West Wing and elsewhere with access to transcripts of President Donald Trump’s phone calls. The Washington Post on Thursday published transcripts of his conversations with the leaders of Mexico and Australia.

Trump counselor Kellyanne Conway told “Fox & Friends” that “it’s easier to figure out who’s leaking than the leakers may realize.” And might lie detectors be used? She said: “Well, they may, they may not.”

Trump’s outbursts against media organizations he derides as “fake news” have led to predictions that his administration will more aggressively try to root out leaks, and the timing of the Justice Department’s announcement — one week after the president complained on Twitter that Sessions had been weak on “intel leakers” — raised questions about whether the attorney general was working to quell the anger of the man who appointed him.

Sessions said in his remarks that his department has more than tripled the number of active leaks investigations compared to the number pending when President Barack Obama left office, and the number of referrals to the Justice Department for potential investigation of unauthorized disclosures had “exploded.”

“This nation must end the culture of leaks. We will investigate and seek to bring criminals to justice. We will not allow rogue anonymous sources with security clearances to sell out our country any longer,” Sessions said in his remarks.

Media organizations also had an often-tense relationship with the Obama administration, whose Justice Department brought more leaks cases than under all previous administrations combined and was criticized for maneuvers seen as needlessly aggressive and intrusive.

That included a secret subpoena of phone records of Associated Press reporters and editors following a 2012 story about a foiled bomb plot, and the labeling of a Fox News journalist as a “co-conspirator” after a report on North Korea. The Justice Department also abandoned a yearslong effort to force a New York Times journalist to reveal his source in the trial of a former CIA officer who was later found guilty of disclosing classified information.

Following consultation with media lawyers, the department in 2015 revised its guidelines for leak investigations to require additional levels of approval before a reporter could be subpoenaed, including from the attorney general. But Sessions and Deputy Attorney General Rod Rosenstein said Friday that they were reviewing how the department conducts leak investigations and whether current regulations impose too many hurdles on their work.

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