 Some observers have disputed this assessment and argued that the operation was carried out by al-Qaida, while others have said that on balance, the available evidence suggests Shiite responsibility.Several of its members are wanted in the United States for their alleged part in the 1996 Khobar Towers bombing.The group is also charged by the FBI with alleged participants Ahmed Al Mughassil, Ali Al Houri, Hani al-Sayegh, Ibrahim Al Yacoub, Abdelkarim Al Nasser, Mustafa Al Qassab, Abdallah Al Jarash, Hussein Al Mughis and a Lebanese "John Doe".