Jeff Sessions, once one of Donald Trump’s favorite surrogates on the campaign trail, fell out of favor with his boss earlier this summer as special prosecutor Robert Mueller’s collusion investigation spilled into the public eye and Trump family members became ensnared in the probe. For weeks, the embattled attorney general served as Trump’s preferred whipping boy. Then, in what was seemingly an attempt to return to Trump’s good graces amid the public flogging, Sessions doubled down on one of the president’s favored issues: intelligence leaks.

Ten days after Trump slammed the head of his own Justice Department of being “very weak” on leaks, Sessions held a press conference in which he pledged that his agency would not hesitate to bring criminal charges against individuals who made such disclosures to the media. “I have this message for our friends in the intelligence community. The Department of Justice is open for business and I have, this morning, this warning: Don’t do it,” Sessions said at a press conference in July, noting that the D.O.J. had tripled the number of leak investigations compared to the Barack Obama administration and was reviewing its policy on media subpoenas. “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.”

Now, Sessions’s war on leaks is coming into focus. The attorney general has proposed subjecting all National Security Council staffers to polygraph tests, according to an Axios report published on Sunday and later confirmed by CNN. Sessions reportedly told associates that he would narrow the scope of the lie-detector tests to the leaks of details—and subsequently, transcripts—of the president’s phone calls with Mexican President Enrique Peña Nieto and Australian Prime Minister Malcolm Turnbull. The idea being that a relatively small number of the administration would have had access to the details of the phone calls and the leaks of Trump’s private conversations with foreign leaders drew ire from both sides of the aisle.

It is unclear from both the Axios and CNN reports what the consequences would be if Sessions did manage to ferret out the leakers or whether he has discussed the idea of polygraph tests with H.R. McMaster, Trump’s national security adviser. It certainly, however, wouldn’t be the first time such a hunt took place. The Obama administration infamously investigated the leak of intelligence about the Stuxnet virus, ensnaring General James Cartwright whom Obama later pardoned. President Richard Nixon also considered using polygraph tests to sniff out individuals who were sharing intelligence with the press. “I don’t know anything about polygraph tests other than they scare the hell out of people,” the former president once said.