BAGHDAD (Reuters) - If Washington doubts there is Iraqi public support for guerrillas killing its troops, it should consider the teenagers who happily watched American blood spill Wednesday. After a roadside bomb ripped through a military vehicle and wounded two soldiers, Iraqi boys rushed out of their homes to survey the damage. "This is good. If they ask me, I will join the resistance. The Americans have to die," said Ali Qais, 15. "They are just here to steal our oil." The U.S. administration has long dismissed the guerrillas as isolated "terrorists" who are Saddam Hussein loyalists or foreign Islamic...