Next came the Mumbai attacks, a strategic counter-move by militants in response to the American plan which has succeeded, in the short term at least, in increasing tensions between the neighbours at the expense of Pakistan's commitment to Fata.

Whatever the final implications of Mumbai, Petraeus is likely to find that the fundamental stumbling block to his plan lies in Pakistan's perceptions of Western involvement in Afghanistan. Pakistani generals are convinced, based on historical precedent, that the presence of foreign troops there will be transient. They regard the vacuum left by the West's inevitable withdrawal from Afghanistan as a vital arena in which to jockey with India, a country as key to the Pakistani military psyche as the Turks are to the Serbs and the Israelis to the Palestinians.

This fear, comprehensive enough in a country that has largely defined itself through its enmity with India, causes Pakistan's military to cling to its concept of Afghanistan as a place of "strategic depth" for its long-term interests, hence past overt support of the Taliban, among others, and the lingering accusations that elements of the ISI continue to support some militant groups as a safeguard for the future.

In Peshawar, I met a former Guantánamo inmate who insisted that during interrogation by the ISI after his arrest in 2001 he had been given a simple choice by his captors.

"They told me ‘Go to fight in Afghanistan or we will hand you over to the Americans'," the man reported. "I met many other prisoners who were given the same option." He had balked at joining the new wave of Taliban insurgents in Afghanistan so was handed to the CIA and sent to Guantánamo.