Wednesday’s explosion in Peshawar, which killed more than 90 people, was the latest in a series that highlights the destabilisation of Pakistan. Western public opinion has turned against the Afghan war, perhaps irrevocably. President Barack Obama is criticised for alleged dithering. Yet the White House is struggling to answer two related and very hard questions. Are western strategic interests in the region vital? And is success plausible, in pursuing them by military means?

The Pakistani journalist Ahmed Rashid, whose books on the Taliban and regional crisis have gained an international audience, argues in the current National Interest that the US must stay the course. If it does not, he says, there is a serious prospect of “Talibanisation” of the entire region and the Taliban is inseparably entwined with al-Qaeda. Neighbouring Tajikistan, Uzbekistan, Kyrgyzstan and Turkmenistan face pauperisation, and consequent Islamic insurgencies against their corrupt and incompetent rulers. Mr Rashid paints a bleak picture of Pakistan’s predicament, with the civilian government too weak to stand up to the army – still obsessed with India – and the economy in freefall. Mr Rashid suggests a danger of a “colonels’ coup”, which installs an Islamabad regime sympathetic to the Taliban.