<p>A BULLETPROOF LandCruiser at high speed bursting out of a tribal compound in Pakistan's South Waziristan region was just the latest infuriating setback in the US's quest to bring down the top of the al-Qa'ida tree.</p>
<p>The car, followed by two armoured vehicles and a phalanx of heavily armed militants able to wipe out dozens of crack troops sent to blast the terrorists from their nest, is believed to have contained Ayman al-Zawahiri, right-hand man to Osama bin Laden.</p>
