Donald Trump's ex-national security adviser has pleaded guilty to mishandling classified material while compiling notes for a book.
John Bolton is a well-known critic of the President's administration and has accused Mr Trump of trying to "intimidate his opponents".
His case is being heard by a US federal court in Maryland, where he will be sentenced on October 28.
Bolton was indicted on 18 counts related to improper handling of the sensitive documents. He originally pleaded not guilty.
But today, he admitted to one charge of illegal retention of classified data, some of which detailed top secret defence plans.
As a result, the former adviser could face up to five years behind bars.
A plea deal could allow him to receive a shorter sentence in prison, or avoid jail altogether, but it is not guaranteed.
If the judge hands him a longer prison sentence or a fine greater than $2.25million (£1.7million), Bolton is allowed to withdraw the guilty plea.
John Bolton pleaded guilty in Maryland today
|GETTY
Bolton admitted the allegations laid against him were accurate after the judge read out the accusations in court.
"I did your honour," Bolton admitted when questioned whether he committed the crime, adding that he was "sorry".
Speaking outside the court, US Attorney Kelly Hayes said Bolton understood the delicacy of classified information and with whom he was able to share the sensitive documents.
She said: "He also knew the damage to national security that could be caused by mishandling that sensitive information.
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Bolton could face up to five years behind bars
|REUTERS
"Nevertheless, as Mr Bolton just admitted, he put our national security at grave risk in violation of the law."
FBI agents searched through Bolton's Maryland home and Washington DC office last summer.
Prosecutors brought the case before the US Department of Justice before the second Trump administration took over the Oval Office.
Bolton served as Mr Trump's national security adviser from April 2018 until September 2019 when he was sacked from the White House's top team.
His biography, published the following year, called The Room Where It Happened, suggested the Commander-in-Chief was unknowledgeable about the state of international affairs.
The White House applied to block its release, insisting the book contained sensitive Government data and had not been approved.
Nevertheless, a judge shot down the request.
The US Department of Justice later launched a probe into any potential wrongdoing regarding the mishandling of secret information, including sharing it with two family members.
The 47th President has dubbed his former adviser a "sleazebag".