American troops who mistakenly killed an Italian secret agent in Iraq fired from a checkpoint set up to boost security for the U.S. ambassador who was on his way to dinner with a general, a U.S. official said on Friday.U.S. embassy spokesman Bob Callahan said Ambassador John Negroponte was traveling on the airport road to meet General George Casey, commander of multinational forces in Iraq, at a U.S. base next to Baghdad airport. “The mobile checkpoint was set up for the security of the ambassador who was on his way to dinner at Camp Victory with General Casey,” Callahan said. “This was a mobile checkpoint that was set up on a temporary basis.”Full Story