WASHINGTON — President Donald Trump is vowing to root out the leakers who contributed to the White House insider accounts that contend some on his team question his judgment, competence and even rationality.

A book by presidential author Bob Woodward and an anonymous New York Times op-ed article, Trump has said, are fiction and lies. But the president nonetheless finds them compelling enough to seek out the leakers of behind-the-scenes stories and quotes. On Friday, Trump said the U.S. Justice Department should investigate the identity of the op-ed writer.

"Eventually, the name of this sick person will come out," he told reporters on Air Force One.

Some things to know about leak investigations:

THE NATURE OF A LEAK

Telling embarrassing stories about a president's behavior is not the same thing as revealing classified information.

The first could be a political risk, which is why administration members from Vice President Mike Pence on down denied being the op-ed writer this week. Still, writing unflattering things about the president isn't a crime.

But the Espionage Act and other federal laws do criminalize unauthorized disclosures about certain national security information, such as surveillance methods. Any leak investigations of classified information tend to go through a complex process at the Justice Department that includes determining whether the information was sensitive and known to few people.

No classified information appears to have been revealed by the anonymous op-ed author. And it's far from clear that the vivid portraits of erratic presidential behavior described by Woodward and the op-ed writer would breach national security.

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SPEAKING OF NATIONAL SECURITY

Trump told reporters Friday that Attorney General Jeff Sessions should pursue the identity of the New York Times essay writer.

"Jeff should be investigating who the author of that piece was because I really believe it's national security," the president said. If the person has a high-level security clearance, Trump said, "I don't want him in those meetings."

The FBI and Justice Department are responsible for investigating federal crimes, but there is no indication of anything illegal having been done in the publication of a newspaper opinion piece critical of the president. It is also extraordinary for a president to demand an investigation by the Justice Department, which is supposed to make investigative and charging decisions without White House interference.

The New York Times opted to publish the unsigned column, which alleges that a "quiet resistance" of senior administration officials is "working diligently from within to frustrate parts of his agenda and his worst inclinations."

Trump earlier dared the Times to do what journalists scrupulously avoid: "If the GUTLESS anonymous person does indeed exist, the Times must, for National Security purposes, turn him/her over to government at once!"

Asked if he would take any action against the Times, Trump said, "We're going to see, I'm looking at that right now."

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THE FALLOUT FROM THESE LEAKS

Trump was asked if, in light of the book and column, he trust the people around him.

"I do, I do," he said. "But what I do is, now I look around the room and I say 'Hey I don't know somebody.'"

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TRUTHTELLING TESTS

Nothing would stop Trump from directing his aides to hunt for leakers among senior officials.

Sen. Rand Paul, R-Ky., who describes himself as a libertarian, says Trump would be justified using lie detectors to find the anonymous essay writer.

Trump wasn't saying Friday whether he'd take the suggestion.

Lie detectors wouldn't be reliable enough to unearth the column author or other sources for sure, studies and a massive federal report have indicated. And polygraphs aren't acceptable as evidence in court.

"At best they are unreliable. The question is how unreliable?" said Indiana University brain sciences professor Richard Shiffrin.

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UNPLEASANT CONSEQUENCES

Meanwhile, Trump is said to be examining the language of the denials issued this week by the highest members of his administration or their spokespeople.

"Everybody very high up has already said it wasn't me. It would be very hard if it was, if they got caught," Trump said. "You'd be shunned for the rest of your life."

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LEAK PROBES PAST

Trump would be far from the first president to hunt for leakers.

During his eight years in office, BarackObama's Justice Department prosecuted nine cases againstwhistleblowersand leakers, compared to three by all other previous administrations. In one of those investigations, the government secretly seized records for telephone lines and switchboards that more than 100 reporters for The Associated Press used in their Washington bureau and elsewhere.

In June under the Trump administration, Reality Winner, 26, pleaded guilty to a single count of transmitting national security information. The former Air Force translator had worked as a contractor at a National Security Agency office in Augusta, Georgia, when she printed a classified report and left the building with it hidden in her pantyhose. Winner told the FBI she mailed the document to an online news outlet.

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DEEP THROAT

Former FBI No. 2 W. Mark Felt first denied, then decades later admitted, being the famous source for Washington Post reporters Woodward and Carl Bernstein in their Watergate coverage that led to the resignation of President Richard Nixon.

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NIXON CONSIDERED POLYGRAPHS FOR THOUSANDS

Prior to the Watergate scandal, Nixon in 1971 considered lie detector tests for an estimated 300,000 federal employees with security clearances, according to a taped presidential conversation played for the House Judiciary Committee looking at the administration's domestic surveillance programs.

Advised the tests would result in mass resignations, he ordered the tests for about 1,000 employees of the State and Defense departments, the CIA and the National Security Council.

A June 1974 Associated Press report quoted Nixon as saying, "I don't know much about these things, but it scares the (expletive deleted) out of them."