From CNN:

Canadian troops fighting Taliban militants in Afghanistan have stumbled across an unexpected and potent enemy—almost impenetrable forests of marijuana plants 10 feet tall. General Rick Hillier, chief of the Canadian defense staff, said Thursday that Taliban fighters were using the forests as cover. In response, the crew of at least one armored car had camouflaged their vehicle with marijuana….

Even successful incineration had its drawbacks.

“A couple of brown plants on the edges of some of those [forests] did catch on fire. But a section of soldiers that was downwind from that had some ill effects and decided that was probably not the right course of action,” Hiller said dryly. One soldier told him later: “Sir, three years ago before I joined the army, I never thought I’d say ‘That damn marijuana’.”

Thanks to Richard for the tip.