Prince Harry cheers on wounded military veterans at the Warrior Games in San Diego

Prince Harry is on hand to support US Army veterans at the Warrior Games in San Diego.

The Duke of Sussex was seen grinning and chatting as he cheered on servicemen and women taking part in events similar to his own Invictus Games.

The royal spoke animatedly to families and clearly joked with those seated around him at the Southern California event.

He later looked relaxed as he posed with veteran United States Special Operations Command gold medalists.

It is the first time Harry has been seen in public since returning from London, where he testified before the High Court in his phone hacking trial against Mirror Group Newspapers. He was the first royal to testify in court in more than a century.

Harry’s own Invictus Games, which he set up in 2014, will take place in Düsseldorf in September.

The event offers those who have suffered illness or injury during or as a result of their service the opportunity to participate in sporting events against other countries.

But earlier this year, organizers of the charity event were urged to distance themselves from Prince Harry following his “insensitive” Taliban revelations in Spare.

Noted publicist Lynne Franks said the Duke of Sussex’s decision to share that he had killed 25 soldiers while serving in Afghanistan “made him look like a complete idiot.”

Harry’s claims, including that he viewed Taliban fighters as “chess pieces” during operations, angered the armed forces who accused the Duke of poor etiquette.

Ben McBean, the Prince’s former Royal Marine and friend, said such comments were ill-advised. Others said Harry put people in danger.

His action in San Diego came as the Department of Homeland Security has until today to respond to a legal demand to release Harry’s US visa papers, which could show he lied about his drug use.

The claims were made last week in the US District Court in Washington, 3,000 miles from the High Court in London, where he testified hours earlier in the lawsuit he brought against the publisher of the Daily Mirror.

The case relates to the Duke of Sussex’s US visa application in March 2020, which may have shown that he had checked ‘no’ when asked about his drug use.

Harry has admitted to using cocaine, marijuana and hallucinogens in his bestselling memoir ‘Spare’ and his Netflix TV series.

If it turns out that Harry lied on his visa forms, he could be removed from the US.

The allegations have been made by The Heritage Foundation, a conservative think tank, which is seeking the release of the Department of Homeland Security documents under the US Freedom of Information law.

Samuel Dewey, the Heritage Foundation’s lead attorney, said the case can take months.

The next stage would be to discuss whether or not the documents themselves should be released.

Dewey criticized the “downright frivolous anti-transparency stance” of President Joe Biden’s administration.

In court cases, the Heritage Foundation focused on two questions on the DS160 visa application form.

The first asks, “Have you ever been a drug abuser or addict?”

The second asks, “Have you ever violated a controlled substance law, or been involved in a conspiracy to violate it?”

The Heritage Foundation, one of Washington’s most influential conservative think tanks, argues that Harry’s admissions about his drug use meant he should have checked ‘yes’.

The Freedom of Information (FoI) application was filed by Nile Gardiner, director of the foundation’s Margaret Thatcher Center for Freedom.

The United States Department of Homeland Security initially rejected the FoI because, due to the personal nature of the information, Harry’s consent was required and he had not given it.

Immigration experts have said Harry’s confessions could lead to him being banned from entering the US by a border agent.

During last night’s hour-long hearing, Judge Carl Nicholas gave the Department of Homeland Security a week to decide whether or not to expedite the case.

A spokesperson for Harry said they would not be commenting “at this time.”