ARLINGTON, Va. (AP) -- President Barack Obama paid tribute Monday to Americans who died in battle, saying people their fellow citizens must "never stop trying to fully repay them" for their sacrifice and noting this is first Memorial Day in 14 years without U.S. forces involved in a major ground war.

Members of the 3rd U.S. Infantry Regiment (The Old Guard) place a flag in front of each headstone at Arlington National Cemetery in Arlington, Va., Thursday, May 21, 2015. "Flags In" is an annual tradition that is reserved for The Old Guard since its designation as the Army’s official ceremonial unit in 1948. They conduct the mission annually at Arlington National Cemetery and the U.S. Soldiers' and Airmen's Home National Cemetery prior to Memorial Day to honor the nation’s fallen military heroes. (AP Photo/Susan Walsh)

Speaking under sunny skies to some 5,000 people on the hallowed grounds of Arlington National Cemetery, including the relatives of the dead, Obama called the burial place "more than a final resting place for fallen heroes"

"It is a reflection of America itself. A reflection of our history, the wars we've waged for democracy, the peace we've laid to preserve it," he said. "It is a reflection of our diversity, of people from different races and creeds who fought for the ideals that bind us as one nation."

His appearance was an annual rite for presidents at the site of the national cemetery nestled among the verdant hills overlooking the Potomac River. It came with the number of troops stationed in Afghanistan reduced to about 10,000, from a peak of over 100,000. Monday's tribute also took place against a backdrop of the increasingly complex U.S. effort to help Iraq defeat a surging Islamic State extremist group that has been gaining momentum in recent weeks, capturing Ramadi there and taking Palmyra in neighboring Syria.

Of Afghanistan, he said "we'll continue to bring them home and reduce our forces further, down to an embassy presence by the end of the year."

"We honor the more than 2,200 patriots who made the sacrifice in Afghanistan," he said there. Earlier Monday, troops still stationed there paused for a moment of silence in honor of those who lost their lives there.

The Arlington observance was among a host of Memorial Day events across the country featuring parades, picnics and tributes. Presaging Monday's solemn event at Arlington was the roar of motorcycle engines throughout the capital Sunday as thousands of bikers saluted veterans with the Rolling Thunder's "Ride for Freedom." That was followed by a concert of patriotic music Sunday evening and Obama's private breakfast at the White House Monday morning with representatives of veteran and military family service organizations, along with the Gold Star Mothers, Gold Star Wives and Sons and Daughters in Touch. A Memorial Day parade was set for downtown Washington Monday afternoon.

"Most Americans don't fully see, don't fully understand, the sacrifices of the 1 percent of the Americans who serve in this all-volunteer force," Obama said in his speech. "Our Gold Star families, our military families, our veterans, they know this intimately."

"Whenever I meet with our "Gold Star" families, as I did this morning, I see that their hearts are still broken, but still full of love," he said. "In the face of unspeakable loss, they represent the best of who we are."

Obama said the markers at Arlington signify the blessings enjoyed by "so many Americans."

"It's a debt we can never fully repay," he said, "but a debt we will never stop trying to fully repay."

Speaking ahead of Obama, Defense Secretary Ash Carter said, "We, your fellow Americans, lack the words to describe what you feel today because try as we may, and try as we do, we can never fully know. But we do know what your sacrifice means to us."
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