Indicative of the growing clout of the Lashkar-e-Toiba (LeT) despite an apparent crackdown by the Pakistani authorities, US security experts believe that the terror group and not al-Qaeda has emerged as the main threat and could well stage the next major attack on the American mainland.

"We are and should be concerned about the threat LeT poses, given its global network," Juan Zarate, deputy national security adviser for counter-terrorism in the Bush administration, told the Chicago Tribune in an interview published on Sunday.