This has been going on for some time in Afghanistan; I discuss it in Islam Unveiled. From Rowan Scarborough in the Washington Times, :
Insurgents and foreign terrorists in Iraq are being financed in part by the illicit drug trade originating in Afghanistan and passing through Iraq to Europe, congressional and defense sources say.
Money from Afghan-produced heroin is being used by terror cells to buy weapons and equipment, and pay Iraqi citizens to conduct attacks on U.S. troops and to plant deadly improvised explosive devices (IEDs), U.S. officials say.
In a Sept. 8 letter to Secretary of State Condoleezza Rice, House International Relations Committee Chairman Henry J. Hyde wrote of an “emerging and dangerous growth of the illicit drug trade in Iraq, especially with heroin, now originating and pouring out of nearby Afghanistan.”
“We can no longer ignore the threat to our national security from drugs in Iraq,” the Illinois Republican said in the letter, obtained by The Washington Times.