WASHINGTON (AP) — President Joe Biden and Vice President Kamala Harris on Monday made their first joint appearance since her election loss when they observed Veterans Day together by laying a wreath at the Tomb of the Unknown Soldier.

The pair then headed to the ceremonial amphitheater at Arlington National Cemetery, where Biden honored the service and sacrifice of America’s military veterans — including those who paid the ultimate price, and their families — during what was his final time speaking there as as commander in chief of the U.S. military.

“It’s been the greatest honor of my life, to lead you, to serve you, to care for you, to defend you, just as you defended us, generation after generation after generation,” Biden said. “You are the greatest fighting force, and this is not hyperbole, the finest fighting force in the history of the world.”

He reminisced about trips to U.S. military installations around the world, and to such historic military sites as Valley Forge and Gettysburg in Pennsylvania.

Biden also announced that the Department of Veterans Affairs is expanding the types of cancers covered under the PACT Act, legislation he signed to expand health care services for veterans who served at military bases where toxic smoke billowed from “burn pits.”

Over 1 million veterans and families have been helped under the law, he said.

The president opened his brief remarks by stating that America’s “truly sacred obligation” is to prepare those it sends into harm’s way and care for them when they come home, or don’t.

“To all the military families, to all those with a loved one still missing or unaccounted for, to all Americans grieving the loss of a loved one who wore the uniform, Jill and I want you to know we see you, we thank you and we’ll never stop working to meet our sacred obligation to you and your family,” he said.

The president’s son, Beau, who first lady Jill Biden helped raise, served in the Delaware Army National Guard and deployed to Iraq in 2008 for about a year. He died of brain cancer in 2015 at the age of 46.

Earlier, at the Tomb of the Unkown Soldier, Biden and Harris, accompanied by Veterans Affairs Secretary Denis McDonough, wore solemn expressions on their faces. They placed their hands over their hearts as the national anthem played before the wreath-laying, and again afterward as “Taps” sounded.

The president and first lady had hosted veterans and members of the military community at the White House before they and Harris and her husband, Doug Emhoff, departed for the hallowed burial ground across the Potomac River from Washington.

It was the first time that Biden and Harris had been seen together in public since the vice president lost last week’s election to former President Donald Trump, though Biden had spoken to both Trump and Harris by phone. The president plans to host the president-elect at the White House on Wednesday.

Before leaving the cemetery, Harris and Emhoff visited a gravesite. The White House did not say who is buried there.

After the observance, Biden flew to his hometown of Wilmington, Delaware but planned to be back in Washington later Monday.