The Pakistani Taliban, a copy of the Afghan extremist movement, have long controlled the tribal area along the Afghan border, which is a sanctuary for militants, including al-Qaeda. But it is their march into the heart of the country that has horrified ordinary Pakistanis, and the wider world. And the threat comes not just from the Taliban to the west. Islamic extremists, who are not part of the Taliban, are already entrenched in Islamabad and across the Punjab, the most populous province, seemingly ready to surface when their moment comes.