In a solemn ceremony at Arlington National Cemetery, Americans mark the 25th anniversary of the downing of Pan Am flight 103.<br/> <br />The service comes as the US, Britain and Libya have pledged their full support to bring those behind the bombing to justice.<br/> <br />270 people were killed in the attack.<br/> <br />U.S. Attorney General Eric Holder addressed those who have lost loved ones.<br/> <br />(SOUNDBITE) (English) U.S. ATTORNEY GENERAL ERIC HOLDER SAYING:<br/> <br />"Although a quarter century has past since the world was shaken and so many lives were devastated by a heinous and cowardly act of terror, no amount of distance or time can ease the pain or erase the loss that was inflicted on that day."<br/> <br />Most of the victims were Americans on their way home from Europe for Christmas. Eleven people died on the ground as the New York-bound jet plunged from the sky after a bomb exploded in its hold some 38 minutes after leaving London's Heathrow airport.<br/> <br />Only one person was ever convicted of in
