Four people have been charged over leaks of information from the Trump administration as the US attorney general pledged to clamp down on unauthorised revelations.
Jeff Sessions warned that government leaks threaten to undermine national security as he took a public stand against the disclosures.
It comes after he was called weak on the matter by President Trump.
His announcement at the Justice Department follows a series of news reports involving the Trump campaign and White House that have relied on classified information.
“No-one is entitled to surreptitiously fight their battles in the media by revealing sensitive government information,” Mr 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.”
The attorney general said the four people charged were accused of unlawfully disclosing classified material or concealing contacts with federal officers.
Mr Trump complained on Twitter last week that Mr Sessions was weak in cracking down on leaks, saying: “Sessions has taken a VERY weak position on Hillary Clinton crimes (where are E-mails & DNC server) & Intel leakers!”
Mr Sessions said in his remarks that his department has more than tripled the number of active leaks investigations compared with the number pending when President Barack Obama left office.
He said the department is reviewing guidelines related to subpoenas of journalists.
“This nation must end the culture of leaks,” Mr Sessions said. “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.”
Under President Obama, the Justice Department brought more leaks cases than all his predecessors combined and was the administration was criticised for manoeuvres seen as needlessly aggressive and intrusive.