Washington — Attorney General Jeff Sessions announced on Friday that the Justice Department was now pursuing three times as many leak investigations as the previous administration, a significant devotion of law enforcement resources to hunt down the sources of unauthorized disclosures of information that have plagued the Trump administration.
Mr. Sessions vowed that the Justice Department would not hesitate to bring criminal charges against people who had leaked classified information. He also announced that the F.B.I. had created a new counterintelligence unit to manage these cases.
“I strongly agree with the president and condemn in the strongest terms the staggering number of leaks,” he said. The announcement by Mr. Sessions comes 10 days after President Trump publicly accused him of being “very” weak on pursuing these investigations in a post on Twitter.
The Sessions news conference came against the backdrop of repeated pressure by Mr. Trump, in public and in private, for the Justice Department and the F.B.I. to hunt down people inside the government who have been telling reporters what was happening behind closed doors.
Mr. Sessions was joined in the news conference by Dan Coats, the director of national intelligence.
The Trump administration has been bedeviled by leaks large and small that have disclosed infighting inside his administration, including the president’s rancorous phone conversations with foreign leaders. Information shared with reporters brought to light what surveillance showed about contacts by Mr. Trump’s associates with Russia and even what Mr. Trump said to Russian visitors in the Oval Office about his firing of James B. Comey, the former F.B.I. director.
Not all leaks are illegal, but the Espionage Act and a handful of other federal statutes criminalize the unauthorized disclosure of certain categories of national-security related information.
In February, Mr. Trump said at a news conference that he told Mr. Sessions to look into leaks — an unusual thing to say, since presidents generally try to avoid appearing as if they are asserting political control over law enforcement.
Mr. Comey also wrote in a memo, recounting one of his conversations with Mr. Trump, that the president had told him to consider putting reporters in prison for publishing classified information.
Mr. Trump has continued to periodically demand a leak crackdown, including criticizing Mr. Sessions in Twitter posts for not doing more. On July 25, for example, the president posted on Twitter, “Attorney General Jeff Sessions has taken a VERY weak position on Hillary Clinton crimes (where are emails & DNC server) & Intel leakers!”
Once rare, leak cases have become far more common in the 21st century, in part because of electronic trails that make it easier for investigators to determine who had access to a leaked document and was in contact with a reporter. Depending on how they are counted, the Obama administration brought nine or 10 leak-related prosecutions — about twice as many as were brought under all previous presidencies combined.