You can either fight a war on drugs or fight an effective war on terror. You can't do both in Afghanistan. Johann Hari shows how the drug war brought the Taliban back from the near-dead. Money quote:
Over the past five years, with British and American military support, a sinister corporation called DynCorps has been going to the fields of the poorest farmers in Afghanistan and systematically destroying them. This is because they are growing opium poppies, used to make heroin that is freely bought on the streets of the West. Emmanuel Reinert, the Executive Director of the Senlis Council, explains, "The Taliban revival is directly, intimately related to the crop eradication programme. It could not have happened if the US was not aggressively destroying crops. It is the single biggest reason Afghans turned against the foreigners."