Attorney General Jeff Sessions said Friday that the Justice Department has more than tripled the number of leak investigations compared with the number that were ongoing at the end of the last administration, offering the first public confirmation of the breadth of the department’s efforts to crack down on unauthorized disclosures of sensitive information.

The announcement seemed designed both to reassure the president, who has criticized the attorney general as being “weak” on leak investigations, and to scare government officials away from talking to reporters about sensitive matters.

Sessions said he was devoting more resources to stamping out unauthorized disclosures, directing Deputy Attorney General Rod J. Rosenstein and FBI Director Christopher A. Wray to actively monitor every investigation, instructing the department’s national security division and U.S. attorneys to prioritize such cases, and creating a new counterintelligence unit in the FBI to manage the work.

Sessions also said he was reviewing the Justice Department’s policy on issuing subpoenas to reporters.

“This culture of leaking must stop,” Sessions said.

(Jenny Starrs/The Washington Post)

President Trump has complained vociferously about unauthorized disclosures of information, particularly when the leaks result in stories that are unflattering to the administration. Many Republicans have argued that the issue deserves as much attention as the investigation into whether Trump’s campaign coordinated with the Kremlin to influence the 2016 election.

[President Trump’s war on leaks, explained]

Sessions, too, has said previously that illegal leaks are “extraordinarily damaging to the United States’ security” and confirmed that such disclosures were already resulting in investigations. Last week, though, Trump wrote on Twitter that his attorney general had “taken a VERY weak position” on “Intel leakers.”

The attorney general did not specify the raw numbers by which leak probes had tripled. The Obama administration initially pursued such cases in historic numbers but grew more averse over time. Officials have said that since the start of the Trump administration, authorities have approved more than half a dozen leak probes and more are expected.

Rosenstein refused to rule out the possibility that journalists would be prosecuted, saying, “I’m not going to comment on any hypotheticals.”

It has long been Justice Department practice in leak probes to try to avoid investigating journalists directly to find their sources. In 2014, then-Attorney General Eric H. Holder Jr. said that as long as he was heading the Justice Department, “no reporter is going to go to jail for doing his or her job.”

The policy instead has been for investigators to first focus on government employees who may be responsible for leaking. In some cases, when the scrutiny of employees has been exhausted, senior Justice Department officials may authorize investigations of journalists, possibly by examining their phone records.

Attorney General Jeff Sessions after a news conference announcing ongoing leak investigations Friday. (Bill O'Leary/The Washington Post)

As a result, leak investigations are often slow moving, and many never lead to charges. Within the FBI and the Justice Department, agents and prosecutors who handle leak cases have long argued that if they could investigate journalists earlier and more aggressively, they could be more successful in prosecuting leak cases.

“We are reviewing the entire process of how we conduct media leak investigations by responding to issues that have been raised by our career prosecutors and agents,” Rosenstein said. “We’re taking basically a fresh look at it. . . . We don’t know yet what, if any, changes we want to make, but we are taking a fresh look.”

Sessions said that the Justice Department must “balance the press’s role with protecting our national security and the lives of those who serve in the intelligence community, the armed services and all law-abiding Americans.”

Prosecutors in the Obama era brought nine leak cases, more than during all previous administrations combined, and in the process called a reporter a criminal “co-conspirator” and secretly went after journalists’ phone records in a bid to identify reporters’ sources. Prosecutors also sought to compel a reporter to testify and identify a source, though they ultimately backed down from that effort.

Holder issued updates in 2015 to the department’s policy on obtaining information from members of the news media, after his Justice Department came under fire for the tactics prosecutors used in bringing such cases.

Sessions made his announcement Friday in the Justice Department’s seventh-floor conference room with Rosenstein, Director of National Intelligence Daniel Coats, and National Counterintelligence and Security Center Director William Evanina. Conspicuously absent were representatives from the FBI, which generally investigates leaks. Rosenstein said that was probably because Wray had just started his job as director of the bureau this week.

Coats said the hunt for reporters’ sources would go well beyond the intelligence agencies. “These national security breaches do not just originate in the intelligence community. They come from a wide range of sources within the government, including the executive branch and including the Congress,” he said.

Sessions said that in the first six months of this year, the Justice Department received nearly as many criminal referrals involving unauthorized disclosures of classified information as it had received in the past three years combined. Though he did not say if it had resulted in a criminal referral, Sessions cited in particular a recent disclosure to The Washington Post of transcripts of Trump conversations with Mexican President Enrique Peña Nieto and Australian Prime Minister Malcolm Turnbull.

Sessions said prosecutors had charged four people with making unauthorized disclosures of classified information or concealing contacts with foreign officers. Most of the cases did not involve journalists.

So far, the Justice Department under Sessions has publicly announced charges in just one leak case related to the media. Reality Leigh Winner, a 25-year-old government contractor, was charged in June with mishandling classified information after authorities said she gave a top-secret National Security Agency document to a news ­organization.

A Justice Department spokesman said that when Sessions mentioned four people who had been charged, he was referring to Winner; Candace Marie Claiborne, a State Department employee charged with concealing her contacts with foreign intelligence agents; Kevin Patrick Mallory, a former CIA officer accused of selling information to China; and Harold T. Martin III, a federal contractor suspected of stealing a massive amount of classified information. Martin was arrested during the Obama administration, though he was indicted in February.

Several prominent conservatives lauded Sessions’s announcement, while open-government and free press groups said it was worrisome. The Reporters Committee for Freedom of the Press said it would “strongly oppose” revising department guidelines on issuing subpoenas to reporters, and Danielle Brian, executive director at the Project on Government Oversight, said leak investigations might inappropriately target well-intentioned whistleblowers.

“Whistleblowers are the nation’s first line of defense against fraud, waste, abuse, and illegality within the federal government, the last thing this administration wants to do is to deter whistleblowing in an effort to stymie leaks,” Brian said in a statement.

Leak cases are difficult to prove and prosecute, and they almost always come with political controversy — especially when the leaks involve providing information to reporters that is arguably in the public interest.

Trump’s presidency has been dogged by a steady stream of information given to reporters by anonymous sources, though not all of those disclosures have involved classified information and many were probably not illegal.

Trump, for example, has complained that former FBI director James B. Comey’s decision to engineer a leak about a conversation he had with the president was illegal, when legal analysts say that is probably not the case.

Comey has conceded that he told a friend to give a reporter information about a request from the president that Comey shut down the bureau’s probe into former national security adviser Michael Flynn. But he said he did not share classified material.

Prosecutors can bring charges against people for sharing information with the public only when classified or other national security material is at issue. Material cannot be classified to conceal legal violations or prevent embarrassment, according to an executive order from President Barack Obama .