A New Terror Threat?

Within hours of the Oct. 29 triple bombing that killed 62 and injured 210 in New Delhi, Indian security services fingered Lashkar-e-Toiba ("Army of the Pure"), a Pakistan-based militant group with links to al Qaeda. On Nov. 10, authorities arrested Tariq Ahmed Dar, a Kashmiri toiletries salesman whom authorities have accused of masterminding the attacks for LeT, and last week announced the arrest of two more men from the Kashmiri capital Srinagar. If the arrests aren't surprising, they are no less troubling.

Out of all the Islamic militant groups in PakistanOsama bin Laden and friends exceptedLeT causes the...