US Defence Secretary Pete Hegseth has awarded a medal to the guard who reprimanded his group at Arlington National Cemetery.

A video of a Veterans Day observance event on Wednesday showed Hegseth, his wife and senior advisers laughing and talking while posing for photos in front of the Tomb of the Unknown Soldier before the guard told them to be quiet.

In a statement, the Pentagon later announced that Hegseth had given Specialist Thomas Iglesias a Joint Service Commendation Medal "for the execution of his duties at the Tomb of the Unknown Soldier".

Photos shared on the defence secretary's X account showed him presenting the medal to Iglesias.

He was accompanied by others whom the Pentagon identified as members of the 3rd US Infantry Regiment, known as the Old Guard, which is responsible for holding vigil over the Tomb of the Unknown Soldier.

"We love soldiers. We love standards. Well done, Specialist. Carry on Patriots," the accompanying text on Hegseth's post reads.

In the video, the army sentinel on duty later identified as Iglesias can be seen stepping towards Hegseth's group and shouting: "All visitors will maintain an atmosphere of silence and respect at all times."

Hegseth (right) awarding the medal to Specialist IglesiasThe Arlington National Cemetery etiquette requests that visitors speak quietly and do not engage in disrespectful or disorderly conduct.

The tomb, which is one of the country's most sacred war memorials, marks the final resting place of an unknown soldier who was killed in World War One.

Chief Pentagon spokesman Sean Parnell said in a statement: "While commemorating this solemn day, a soldier correctly and respectfully reminded everyone to maintain decorum.

"The Secretary and the entire Department have always honoured - and will always honour - the sacrifices our military men and women have made to keep America safe."

A service member from the 3rd Infantry Regiment stands watch over the tomb 24 hours a day and has done so since 1948.

It is not unusual for them to admonish visitors to the site, according to the BBC's US partner CBS News. They reportedly do so a few times a day.

Defence Secretary Pete Hegseth and First Lady Melania Trump bow their heads in prayer during a Veterans Day ceremony at Arlington National Cemetery

Earlier, President Donald Trump, Vice-President JD Vance and other top officials attended the annual wreath-laying at the cemetery.

During his speech at the ceremony, Trump offered his gratitude to uniformed service members who have fought for the country. He also touted what he sees as his administration's success in the Iran war.

Trump also pointed out Hegseth during the ceremony, saying he's done a "fantastic job" as defence secretary.

On Tuesday, an effort to impeach the defence secretary under accusations that he waged war on Iran without congressional authorisation failed on Capitol Hill.

Hegseth has called the impeachment efforts a "farce" and a "stunt". (BBC)