US Attorney General Jeff Sessions, taking up an issue that has infuriated President Donald Trump, went on the attack against a "culture of leaking" today, saying such leaks were hampering the government's ability to protect the country.
The Justice Department has tripled the number of investigations into unauthorised leaks of classified information and four people have already been charged, Sessions said.
No government can be effective when its leaders cannot discuss sensitive matters in confidence or to talk freely in confidence with foreign leaders
"We are taking a stand," he told reporters as he announced administration efforts to battle what he called "the staggering number of leaks undermining the ability of our government to protect this country."
"This culture of leaking must stop," he said.
Sessions did not immediately give the identities of the four people charged, but said they had been charged with unlawfully disclosing classified information or concealing contacts with foreign intelligence officers.
Trump has repeatedly voiced anger over a steady stream of leaks to the media about him and his administration since he took office in January. Some have been related to probes into Russian meddling in the 2016 US presidential election, others have concerned infighting in the White House.
In the latest high-profile leak, the Washington Post published transcripts on Thursday of phone calls that Trump had in the early days of his administration with Mexican President Enrique Pena Nieto and Australian Prime Minister Malcolm Turnbull.
"No government can be effective when its leaders cannot discuss sensitive matters in confidence or to talk freely in confidence with foreign leaders," Sessions said of that case.
Sessions was accompanied by Director of National Intelligence Dan Coats, who said leaks of classified information endangered national security. He said such national security breaches came from a wide range of sources, including the executive branch and Congress.
"We simply will not tolerate the illegal release of classified information," Coats said.