ANALYSIS - Embattled Pakistan faces its worst-case scenario

By Andrew Marshall, Asia Political Risk Correspondent

SINGAPORE (Reuters) - The worst-case scenario facing Pakistan -- prolonged insecurity with militants launching bloody attacks on the key pillars of the state -- is no longer just a risk for markets and Western policymakers to fret over.

It is already here.

A week of audacious attacks by al Qaeda-linked Islamist fighters -- including a brazen assault on the main army headquarters -- has killed more than 100 people and proven that Taliban militants and their allies are far from defeated.

"The Taliban attackers demonstrated that despite losing the campaign in the Swat Valley this summer, they retain the capacity for terror in the heart of Pakistan -- striking, in effect, into the Pentagon of Pakistan," said Brookings fellow Bruce Riedel.

But that does not mean they are anywhere near winning a meaningful victory. Pakistan faces months or years of traumatic asymmetric warfare against militants who can create chronic insecurity but have no prospect of seizing control of the state.

However successful they may be in waging a destabilising guerrilla war, a few thousand tribesmen and militants cannot hope to defeat the world's sixth-largest military.

The growing risk that militant groups in the Punjab are making common cause with the Taliban to attack the state, as explicitly seen in the weekend's attack in Rawalpindi, is a concern but does not alter the fundamental military arithmetic.

A second key consideration is that outside tribal areas, the Taliban could never hope to win widespread popular support.