WASHINGTON — President Barack Obama is asking Americans to observe Memorial Day not just with barbecues and family time but by remembering and honoring the U.S. troops who have lost their lives in service. Obama, who has sent thousands of troops into war in Afghanistan, used his weekly radio and Internet address Saturday to reflect on what the country owes its men and women who have died in uniform. "On this day, we honor not just those who've worn this country's uniform, but the men and women who've died in its service; who've laid down their lives in defense of their fellow citizens; who've given their last full measure of devotion to protect the United States of America," Obama said. "These are the men and women I will be honoring this weekend." Obama said fallen troops should be honored not just with words but with deeds, including ensuring that combat troops have the support they need in the field and that veterans get the assistance they need when they return home.