Leading article: Pakistan's war of necessity

The conflict with the Taliban in the north of Pakistan has undergone a gear change. The bomb that yesterday killed 41 people in the Swat Valley was targeted on a security convoy in an area the military has recently retaken from militants. Two days ago Taliban-affiliated forces launched an attack on the national headquarters of the Pakistani Army. There have been other major attacks.

The situation may look more out of control but the mayhem may signal the very opposite. In the past, Islamists in Pakistan's bureaucracy, military and secret police, the ISI, have driven policy. A blind eye was often turned that gave the Taliban considerable freedom of operation inside Pakistan on the apparent belief that the ISI could allow al-Qa'ida forces to operate in Afghanistan and yet adequately contain their influence inside Pakistan. That seems to have changed after Taliban forces seized control of Swat, ending the tacit truce with the Pakistani government. All summer the Pakistan army has engaged in a sustained campaign to oust them. Now it is preparing to move on the Taliban stronghold in South Waziristan. The recent attacks are seen as Taliban warnings against this. But the operation is imminent, with air strikes already begun.

All this is happening as Washington is divided over whether it can begin to make a distinction between Afghan nationalists in the Taliban, who are no threat to US domestic security, and ideological al-Qa'ida supporters, who are.

Current events on the ground would caution against such wishful thinking. Jihadists have claimed that recent attacks are not just a reaction to the army's recapture of Swat but also in retaliation for the US killing of a key al-Qa'ida commander in southern Somalia. Recent intelligence suggests that Taliban forces fighting Nato have more than trebled since 2006 which suggests that there is more to the upsurge than can be explained by Afghan nationalism.

That is why a new sense of commitment among Pakistan's military and intelligence establishment to an all-out conflict with extremist forces is to be welcomed and supported. This is not a war of choice. It is a war of necessity.