“An American was one of four suicide bombers who took part in a recent coordinated assault in Syria, according to an Al Nusrah Front sharia official who is active on Twitter. On May 25, the Al Nusrah Front, al Qaeda’s official branch in Syria, announced that the joint attacks had been launched in conjunction with another rebel group, Suqour al Sham. A rumor circulated on Twitter that one of the four suicide bombers was an American, but there was no official confirmation from either of the groups responsible for the attacks.”
Source: American took part in suicide bombings, Al Nusrah Front sharia official says – The Long War Journal