With his job performance reviewed negatively on Twitter by his boss, Attorney General Jeff Sessions convened a press conference to declare a crackdown on illegal leaks to the press.

“We are taking a stand. This culture of leaking must stop,” Sessions said at the August event, shortly after President Trump fumed that the attorney general was taking a “ VERY weak” approach to disclosures of classified information.

[White House national security team fingered in Trump’s Putin call leak]

The Justice Department "has more than tripled the number of active leak investigations compared to the number pending at the end of the last administration,” Sessions said at the press conference.

But since then, no high-profile case has been brought against an alleged leaker, despite Sessions telling a congressional committee in November that there were 27 active probes.

Probable criminal leaks still uncharged include the disclosure of transcripts from Trump’s calls with foreign leaders and information on NSA intercepts involving former Trump adviser Michael Flynn.

Experts are divided on what to make of the lull, which follows a torrent of anti-Trump leaks on the heels of President Obama’s "war on leaks" with superlative use of the Espionage Act to punish speaking with reporters.

"I get the impression – and it is nothing more than an impression – that DOJ has shown somewhat less zeal for going after leakers. That may reflect the general view of official Washington about Mr. Trump," said Robert Deitz, general counsel of the National Security Agency from 1998 to 2006.

Deitz, who also served in senior legal roles at the CIA, the Defense Department and the National Geospatial-Intelligence Agency, doesn’t take Sessions’ claim of more investigations at face value.

"As used by Mr. Sessions, I would not think of the word 'investigation' as a term of art with a rigorous definition," he said.

Not all leaks are criminal, and it’s conceivable factors such as widespread use of encrypted communication technology is frustrating investigators.

So far under Trump, only NSA contractor Reality Winner has been charged under the Espionage Act for press contact — in June, after allegedly mailing a classified document to a news outlet. The outlet is believed to be The Intercept, which reported on a top-secret review of Russian attempts to hack election officials in 2016.

Winner reportedly was one of six people who printed the document, and the only one who contacted the news outlet. She allegedly confessed and currently is being held pending trial.

Obama’s administration brought eight Espionage Act cases against people accused of giving information to the press. The law carries stiff penalties and no room for a public-interest defense, and historically was used to target spies, with only three pre-Obama cases against press sources.

Former CIA operative John Kiriakou, one of the press contacts hit with Espionage Act charges under Obama, said he’s hopeful that the Trump administration is taking a lighter approach.

"President Trump seems to have settled on a policy to not target national security whistleblowers, with the notable exception of Reality Winner. That's good for the country," Kiriakou said.

"The self-professed 'most transparent president in history' was anything but. [Obama] was the enemy of transparency," he said.

"His attorney general, Eric Holder, actively targeted any national security employee who went public with evidence of waste, fraud, abuse, or illegality and did so with the full support and assistance of the FBI, the CIA, and the DNI," he said. "The goal was to silence those national security officers and to frighten others who were considering doing the same. Those days may be over."

Kiriakou led a CIA team that captured al Qaeda operative Abu Zubaydah in 2002, but later publicly criticized interrogation tactics he considers torture. Kiriakou was charged under the Espionage Act after giving a then-freelance journalist the name of an active CIA employee, which the reporter did not publish. He pleaded guilty in 2012 to a lesser charge and served nearly two years in prison.

Another of the eight Obama-era Espionage Act indictees, former NSA senior executive Thomas Drake, offered a less rosy take.

"Leak investigations continue under Trump, a continuum from Obama. And yet White Houses under both administrations [are the] greatest leaker of all," Drake said. He and other pro-whistleblower activists point out that powerful people who carelessly handle secrets or leak in their own interests, such as former Secretary of State Hillary Clinton and former CIA Director David Petraeus, rarely face harsh criminal penalties.

Drake was charged with violating the Espionage Act in 2010 after communicating with a Baltimore Sun journalist reporting on ineffective and expensive NSA programs, including the abandoned $1.2 billion Trailblazer surveillance program, which was chosen over a cheaper, more privacy-protecting alternative. Drake pleaded guilty to a single misdemeanor in 2011.

"No high profile cases? What about the ongoing Reality Winner case as well as several other [national security] cases?" he said. "And Sessions has stated that there are over two dozen ongoing 'leak' investigations. By definition all 'leak' cases involve the media, either directly or indirectly."

Although Winner stands alone in being publicly charged with providing information to journalists, Sessions said in August that four people, presumably including Winner, had been charged with "unlawfully disclosing classified material or with concealing contacts with foreign intelligence officers."

Justice Department spokesmen did not respond to a request for fresh data, but the number of cases involving classified information increased when former NSA employee Nghia Hoang Pho was charged in late November, and almost immediately pleaded guilty, to unlawfully retaining top-secret records reportedly taken by Russian hackers through Kaspersky Lab anti-virus software on Pho’s personal computer.

Steven Aftergood, director of the government secrecy project at the Federation of American Scientists, said it’s too soon to draw conclusions about the Trump administration.

"It can sometimes take years for a leak to result in an indictment," Aftergood said. "Aside from that, there are other penalties available to the government besides criminal prosecution — such as loss of clearance, termination of employment, and more."

Aftergood said that "we can only see the visible part of the iceberg, not what's below the surface. We can talk about what we know, but it's important to be aware that we don't see the full picture."

He notes that the first leak case under Obama — against FBI translator Shamai Leibowitz, for allegedly giving information to a blogger — was not filed until December 2009, the end of Obama's first year in office. "It is still early to draw comparisons with the Trump administration,” he said.

Aftergood and Deitz, the former NSA attorney, find common ground analyzing Obama’s record.

“Obama set new standards of aggressiveness in prosecuting and punishing leaks,” Aftergood said.

“That is my instinct, based only on the number of you guys who were investigated,” Deitz said, referring to journalists.

The Obama administration waged a long legal battle to compel testimony from a New York Times reporter in the Espionage Act case against CIA employee Jeffrey Sterling, labeled a Fox News reporter a suspected criminal "co-conspirator" in the Espionage Act case against State Department official Stephen Kim, and secretly acquired Associated Press phone records in the case against Donald Sachtleben, a former FBI agent.

Two of the most prominent Obama-era Espionage Act cases — against mass surveillance whistleblower Edward Snowden and WikiLeaks source Chelsea Manning — involved politically motivated disclosures, but others had murkier motivates.

Sterling, who had alleged racial discrimination at the CIA, was convicted of exposing an allegedly bungled plot to undermine Iran’s nuclear program, Kim pleaded guilty to sharing an analysis of North Korean intentions, and Sachtleben — already jailed for child porn — pleaded guilty to disclosing a foiled al Qaeda airplane bomb plot, a disclosure whose alleged damage was compounded by former counterterrorism official Richard Clarke saying on TV that the U.S. had "insider control" of the plot. Clarke was told the detail by Obama adviser John Brennan, but neither man faced charges and Brennan became CIA director.

Deitz said even if a crackdown intensifies under Trump, leaks are unlikely to stop.

"I do not believe that leaks can be stopped by a 'war,' in the absence of an attack on civil liberties that Americans would never tolerate," he said.