AP Photo

It's easy to overlook the killing of a single person in violence-plagued Pakistan, not least in Karachi, a seaside metropolis ever in danger of boiling over into sectarian bloodshed. But the murder of a Saudi diplomat by unknown assailants ought to raise eyebrows. Saudi Arabia's tangled, pervasive influence in Pakistan has been well documented (including by me), so an attack on one of the kingdom's officials is not just surprising, but a possible harbinger of larger tensions. Before the shooting, bombs had earlier been hurled at the gates of the Saudi consulate (those ...