The US Government has urged the civil courts in Virginia to protect the employment details of Harry Dunn’s alleged killer in the interests of “national security”.

The teenager’s parents, Charlotte Charles and Tim Dunn, brought a damages claim against Anne Sacoolas and her husband following a fatal road crash outside RAF Croughton in Northamptonshire in August 2019.

Sacoolas, 43, was able to return to the US 19 days after the crash after diplomatic immunity was asserted on her behalf by the US Government.

She was later charged with causing death by dangerous driving by the CPS but an extradition request, submitted by the Home Office, was rejected by the US State Department in January last year.

In general terms, the United States seeks protection… because of the impact the disclosure of information regarding the Government in this litigation could reasonably be expected to have on national security.

On Friday, lawyers acting on behalf of the US administration filed a proposed “protective order” ahead of the suspect’s deposition in the damages claim next month.

The motion states that “although defendants were employees of the United States Government at the time” of the crash, “information concerning the United States Government has little to no relevance to an adjudication of any remaining issues in this case”.

It continues: “In general terms, the United States seeks protection … because of the impact the disclosure of information regarding the Government in this litigation could reasonably be expected to have on national security.

“The United States respectfully requests that this court enter a protective order foreclosing discovery or disclosure of information in this civil action implicating the United States Government that is in any way, either directly or indirectly, related to the defendants’ or any other individuals’ employment with the United States Government.”

The Dunn family’s spokesman has said they will tell the US Government the motion will be “resisted strenuously”.

The damages claim, brought against both Sacoolas and her husband Jonathan, has unearthed a great deal of previously unheard material, such as the State Department roles held by the couple at the time of the crash.

The Alexandria District Court in the US State of Virginia heard the pair’s work in intelligence was a “factor” in their departure from the UK – with the Sacoolases leaving for “security reasons”.

Mr Dunn’s parents gave legal testimony in the case earlier this month.

Reacting to the proposed order submitted on behalf of the US Government, the Dunn family’s spokesman Radd Seiger told the PA news agency: “We have just been made aware of this development in the US civil claim overnight.

“We are analysing it and the family will be seeking legal advice from their US lawyers.

“It now appears that Mr and Mrs Sacoolas have brought in their employers, the US Government, to help them minimise what happened to Harry on the night he died in an attempt to prevent both the family and public at large from knowing the full truth.

“The US Government have asked the parents to consent to their application to court, who in turn have told them it will be resisted strenuously.”

The civil claim is one of a number of legal processes the Dunn family have entered into in order to secure justice for their son.

Last month, Foreign Secretary Dominic Raab said the path was now clear for the UK to push for a form of “virtual trial or process” in the case.