Biden, in Memorial Day speech, says Americans must continue upholding democracy

President Joe Biden, in his Memorial Day message to the nation, said Americans have a "responsibility" to uphold democratic ideals for which so many service members and their families have sacrificed

In a speech at the amphitheater at Arlington National Cemetery, on a cloudy morning in Washington, Biden honored those who served in every major conflict since the Civil War.

“Every generation, our fallen heroes have brought us closer,” he continued. “Today we are not just fortunate heirs of their legacy. We have a responsibility to be the keepers of their mission. That truest memorial of their lives. The actions we take every day to ensure our democracy endures. The very idea of America endures.”

Biden, addressing military families of those who have lost loved ones, said he knows how difficult it can be after losing his son Beau to brain cancer in 2015. President Biden on Monday reiterated his belief the cancer stemmed from exposure to burn pits during his deployment in Iraq.

"I know it hurts. The hurt is still real, still raw," he said, noting this week will mark the 9th years since Beau's death. "The pain of his loss is with me everyday as it is for so many of you. Still sharp, still clear but so is the pride I feel in his service as if I can still hear him saying, 'It’s my duty, dad, it’s my duty.'"

"On this day we came together again to reflect, to remember but above all, to recommit to the future they fought for," he added. "A future grounded in freedom, democracy, opportunity and equality not just for some but for all."

Defense Secretary Lloyd Austin and Gen. C.Q. Brown, chairman of the Joint Chiefs of Staff, also delivered remarks during Monday's ceremony thanking service members and their families.

Before his remarks, Biden took part in the traditional wreath-laying at the Tomb of the Unknown Soldier at Arlington National Cemetery. After presenting the wreath at the memorial, also known as the Tomb of the Unknowns, Biden made the sign of the cross.

He was joined at the ceremony by Vice President Kamala Harris and Secretary Austin. The three leaders stood with their hands over their hearts as the taps played.

Earlier Monday, Biden hosted a breakfast at the White House with administration officials, military leadership, veterans and Gold Star family members to mark Memorial Day.

Next week, President Biden will travel to Normandy, France to mark the 80th anniversary of D-Day.

In his speech on Monday, Biden highlighted those who fought on that day as "members of the greatest generation who, 80 years ago next week, liberated a continent and saved the world."

The president went on to praised all those who've battled against fascism, communism and terrorism.

"Decade after decade, tour after tour, these wars fought for our freedom and the freedom of others because freedom has never been guaranteed," Biden said.

"Every generation has to earn it, fight for it, defend it in battle between autocracy and democracy, between the greed of a few and the rights of many," he continued. "It matters. Our democracy is more than just a system of government. It is the very soul of America."

As President Biden spent the morning at Arlington National Cemetery, former President Donald Trump -- the presumptive Republican nominee and Biden's 2024 challenger-- posted some messages to his social media platform to mark Memorial Day.

One post included a photo of Trump giving a salute with the caption, "We can never replace them. We can never repay them, but we can always remember. Today, that is what we are doing -- we remember."

In a subsequent post, however, Trump briefly mention Memorial Day before attacking E. Jean Carroll, who successfully brought a defamation case against him, and Judge Arthur Engoron, who oversaw his civil business fraud trial in New York.

“Happy Memorial Day to All, including the Human Scum that is working so hard to destroy our Once Great Country, & to the Radical Left,” Trump wrote.

ABC News' Lalee Ibssa contributed to this report.