WASHINGTON - President Donald Trump is expressing his nation's "boundless and undying" gratitude to Americans who have fallen in battle and to the families they left behind.

Trump hailed heroes in his first Memorial Day remarks as president at Arlington National Cemetery. He told the stories of two soldiers who died in Afghanistan, Green Beret Capt. Andrew D. Byers of Colorado Springs and Christopher D. Horton of the Oklahoma National Guard. He also hailed Bob Dole, the former senator who suffered lifelong injuries in World War II and attended Monday's ceremony.

And Trump singled out his homeland security secretary, John Kelly, for whom military sacrifice is close to home.

Kelly led the U.S. Southern Command and lost his son, Robert Kelly, who stepped on a land mine on a Marine patrol in Afghanistan. John Kelly's other son, Johnny, is preparing for his fifth military deployment. And Kelly's son-in-law Jake is a wounded warrior.