Thousands of Pakistani troops have been clambering up the ragged border peaks of southwest of Islamabad for more than a week to seal off isolated escape routes out of Afghanistan. In Afghanistan’s Tora Bora region, U.S. commandos and Afghan guerrillas still poke through the caves and bunkers where fighters from the al-Qaeda organization made their last stand. But after two-and-a-half months of bombing and a manhunt aided by the world’s most advanced intelligence-gathering devices, Osama bin Laden is still not in anybody’s gun sights.