ISLAMABAD, Pakistan (AP) — Taliban militants based near the Afghan border and their al-Qaida allies are the most likely suspects behind a massive truck bombing at Islamabad’s Marriott Hotel, officials and experts said Sunday. At least 53 died in the explosion, including two U.S. Defense Department employees and the Czech ambassador. The truck sat burning and disabled at the hotel gate for at least 3 1⁄2 minutes as nervous guards tried to douse the flames before they, the truck and much of the hotel forecourt vanished in a fearsome fireball on Saturday night, according to dramatic surveillance footage.