He said the war in Iraq has ended after nine years and is "winding down" in Afghanistan. But he conceded that the pain of war lingers for the families of those lost in battle, noting mourners can be seen daily at Arlington National Cemetery daily, not just on Memorial Day.
"These 600 acres are home to Americans from every part of the country who gave their lives in every part of the globe," said the president, speaking under a brilliant sun before a large audience, including many uniformed servicemen and women, at the cemetery, after taking part in the traditional laying of a wreath at the Tomb of the Unknowns.
The president promised war veterans that "we will be there for you," to ensure that troops returning home from battle get the benefits they deserve.
Preceding Obama, Defense Secretary Leon Panetta said that "all the men and women who rest here are a constant reminder that freedom is not free." He noted that some 6,400 men and women have died defending America since the terror attacks of Sept. 11, 2001.
Obama was traveling later Monday to the Vietnam War Memorial to give special recognition to the troops who served and died in that war.
In this election year, Obama has been reminding his audiences about the end of the war in Iraq and the move to bring all troops home from Afghanistan by 2014. In a campaign aid released last week, he credits U.S. servicemen who helped in the raid that killed Osama bin Laden.
With so many troops returning home from their service, Obama says the U.S. needs to return the favor.
"We have to serve them and their families as well as they have served us," Obama said in his weekly radio and Internet address. "By making sure that they get the health care and benefits they need; by caring for our wounded warriors and supporting our military families; and by giving veterans the chance to go to college, find a good job and enjoy the freedom that they risked everything to protect."
The White House said the gathering at the Vietnam Veterans Memorial War would mark the beginning of a 13-year program to honor those who served during the Vietnam War.
Republican Mitt Romney was scheduled to appear Monday with Arizona Sen. John McCain, the 2008 GOP nominee, in San Diego, home to a large number of military personnel and veterans. Romney has made the case that too many veterans are returning home to poor job prospects, casting blame on Obama's economic policies.
A Bureau of Labor Statistics report in March found that 12.1 percent of U.S. Armed Forces veterans who served on active duty after September 2001 were unemployed in 2011. The unemployment rate for all veterans was 8.3 percent.
Veterans could play a significant role in the 2012 election. Exit polls in 2008 showed that Obama was supported by about 44 percent of voters who said they served in the military, while 54 percent voted for McCain, a former Navy pilot who was a prisoner of war for more than five years during the Vietnam War.
A poll released Monday by Gallup found that 58 percent of veterans support Romney and 34 percent back Obama. The results were based on a sample of 3,327 veterans who are registered voters and had a margin of error of 2 percentage points.
Several closely watched states in the election have large blocs of military voters. Florida, home to several military installations, has more than 1.6 million veterans, according to the Veterans Administration. Pennsylvania has nearly 1 million veterans, while Virginia and North Carolina each have about 800,000 veterans living in their states.
The president and first lady Michelle Obama started the day with a breakfast at the White House for families who have lost loved ones in combat.