Robert Birchum is going to jail for three years.
The 55-year-old former US Air Force intelligence officer was sentenced at the beginning of June by a court in Florida for keeping classified documents at his home and other unauthorised locations.
It was just the most recent example of how the United States government takes its secrets very seriously.
There are strict rules governing who can have access to classified material and the locations in which such documents can be viewed, stored or discussed.
In the Birchum case, he pleaded guilty last February to unlawfully possessing and retaining classified documents relating to the national defence of the United States.
Prosecutors maintained that in 2017 it had been discovered that Birchum knowingly removed more than 300 classified files or documents, including more than 30 items marked top secret, from authorised locations. They claimed these classified materials were kept in his home, his overseas officer’s quarters and a storage pod in his driveway.
Within the US system there are three main degrees of classification – confidential, secret and top secret.
But even above those there are the most highly classified records which required special compartmentalised clearances to access.
Experts in national security maintain that very secret documents can contain the identity of sources, which, if leaked, could lead to them being in danger.
In buildings such as the White House, the US Capitol, the Pentagon and other defence and intelligence facilities, politicians, military personnel and other officials reviewing secret information go to a specially designed room, known as an SCIF.
They leave phones and watches and other devices that connect to the internet outside. Once inside, they can read or be briefed on sensitive information without anyone eavesdropping.
Some of these facilities are portable and can be set up quickly if senior figures are on the move.
There are even SCIFs in some universities where research staff can discuss sensitive projects with government officials or defence contractors.
All of this secrecy does not come cheap. In 2017 the Information Security Oversight Office, the agency tasked with oversight of the system, estimated the US government spent $18.39 billion on security classification.
Breaches of these secrecy rules can lead to dismissal, loss of security clearance or even prosecutions.
Where breaches of security rules are suspected, rank or status does not matter, although some experts say those at the top are more likely to receive fines than imprisonment.
Donald Trump will not be the first senior public figure to face prosecution in relation to the handling of classified information.
In 2005 Sandy Berger, the former national security adviser in the Clinton administration, was fined $50,000 and sentenced to community service and probation after being found to have hidden documents from the National Archives in his clothes and taken them out of the building.
He said at the time that he needed them to prepare for dealing with the commission investigating the 2001 attacks on the World Trade Center and the Pentagon.
In 2015 David Petraeus, one of the most prominent American generals in the wars in Afghanistan and Iraq and later head of the CIA, was sentenced to two years’ probation and a $100,000 fine for providing classified information to his biographer, with whom he was having an affair.
In 2019 a former National Security Agency contractor Harold Martin was sentenced to nine years after investigators found thousands of pages of documents, some marked “secret” or top secret” in his home.
US president Joe Biden is also under investigation over how he handled classified material.
Attorney general Merrick Garland appointed a special counsel in January after classified documents from the Obama administration were found at the president’s former office in Washington and his home in Wilmington, Delaware.
At the beginning of June the US Department of Justice said an investigation into former vice-president Mike Pence regarding the discovery of classified material in his home had been closed. It said he would not face charges.
Earlier this year, Pence’s lawyers said “a small number” of classified materials had been found in his home in Indiana.
The FBI later conducted a five-hour voluntary search of the property and discovered another classified document.