Herlmand's Opium Crop

According to this report, there is likely to be a record opium crop in Afghanistan's Helmand province this year. The central premise of 'Death Force', my upcoming thriller from Headline, is that the opium money is being used to finance the war against the British Army there. They won't start winning the war until they cut off the suppply of money. It is a pretty simple point, and one that makes a good basis for a story. But if it has occured to me, it must have occured to someone in the Army as well? Surely some raids on the drugs lords are taking place - and if not, why not?