Pakistanis do not doubt that President Obama's troop buildup will give U.S. and allied forces more wherewithal to uproot Taliban militants from their strongholds in Afghanistan. What worries them is that the strategy will push Afghan Taliban over the porous border and bolster the ranks of brethren militants in Pakistan's tribal areas, security experts say. Pakistanis remain skeptical that Obama's new blueprint for winning the war in Afghanistan will pacify their volatile, unstable neighbor to the west. They put little, if any, trust in Afghan President Hamid Karzai, whose government has been crippled by widespread corruption, and they doubt that...