ARLINGTON, Va. — President Barack Obama saluted Americans who died in battle Monday, saying the country must "never stop trying to fully repay them" for their sacrifices and noting the first Memorial Day in 14 years without U.S. forces involved in a major ground war.Speaking under sunny skies to some 5,000 people on the hallowed grounds of Arlington National Cemetery, Obama called the burial place "more than a final resting place for fallen heroes.""It is a reflection of America itself.