WASHINGTON — President Obama paid tribute Monday to the men and women who have died defending America, pointing to Vietnam veterans as an under-appreciated and sometimes maligned group of war heroes who remained true to their nation despite an unwelcome homecoming.

“You were sometimes blamed for the misdeeds of a few,” Obama said at the Vietnam War Memorial. “You came home and were sometimes denigrated when you should have been celebrated. It was a national shame, a disgrace that should have never happened.”

“Even though some Americans turned their backs on you, you never turned your back on America,” Obama said.

Marking Memorial Day at both the black granite wall honoring more than 58,000 soldiers who died in the Vietnam War, and earlier at Arlington National Cemetery across the Potomac River from the capital, Obama noted that for the first time in nine years, “Americans are not fighting and dying in Iraq,” and the nation was winding down its role in the conflict in Afghanistan.

“After a decade under the dark cloud of war, we can see the light of the new day on the horizon,” Obama said to an audience gathered at the Arlington amphitheater lined with American flags under a warm, brilliant sun.

In this election year, Obama said the nation must remain committed to providing for the families of fallen soldiers and help returning service members seeking a job, higher education or health care benefits. “As long as I’m president, we will make sure you and your loved ones will receive the benefits you’ve earned and the respect you deserve,” Obama said. “America will be there for you.”

Obama said sending troops into harm’s way was “the most wrenching decision that I have to make. And I can promise you I will never do so unless it’s absolutely necessary.”

As he seeks re-election, Obama has reminded audiences about the end of the war in Iraq and the move to bring all troops home from Afghanistan by 2014. And in a campaign ad released last week, he credits U.S. servicemen who helped in the raid that killed Osama bin Laden.

Republican presidential candidate Mitt Romney, meantime, promised to maintain an American military “with no comparable power anywhere in the world.”

The presumptive Republican presidential nominee appeared with Sen. John McCain of Arizona, the GOP’s 2008 presidential candidate, before a crowd in San Diego estimated at 5,000 in what was billed as a Memorial Day service, not a campaign event.

But Romney nevertheless drew clear contrasts with Obama.

At least 1,851 members of the U.S. military have died in Afghanistan as a result of the U.S.-led invasion in 2001, according to the latest Associated Press count.

Despite the human cost of the war, Allen said the soldiers who have fallen did not die in vain.

“While our brothers and sisters fell in a place far from home, far from their families, the values for which they stood and for which they lived and for which they died occupy an enduring place in our hearts,” said Allen. “Those values: freedom, duty, selflessness and sacrifice.”