WASHINGTON  President Obama hailed the sacrifice and determination of the nation’s military on Wednesday as he delivered a Veterans Day tribute at Arlington National Cemetery, a hallowed place where he said the “grief remains fresh.”

As he weighs a decision to escalate the war in Afghanistan, Mr. Obama called on Americans to honor the sacrifices that men and women in this generation  and those who have gone before  have given to protect the country.

“For the better part of a decade, they have endured tour after tour in distant and difficult places,” Mr. Obama said. “They have protected us from danger and they have given others the opportunity for a better life. To all of them, to our veterans, to the fallen and to their families, there’s no tribute, no commemoration, no praise that can truly match the magnitude of your service and your sacrifice.”

The president came to Arlington National Cemetery, just across the Potomac River from the White House, to lay a wreath at the Tomb of the Unknowns. Light raindrops fell on a cool morning as Mr. Obama bowed for a moment of reflection. He placed his hand over his heart as a lone bugler played “Taps.”