It's a war backed by pharmaceutical companies. They influence how doctors treat pain.

http://www.npr.org/sections/thetwo-way/2017/05/31/530929307/...

Here's something... curious. Poppy production was virtually wiped out in Afghanistan: http://www.nytimes.com/2001/05/20/world/taliban-s-ban-on-pop...

Then we invaded. Now it's high: https://upload.wikimedia.org/wikipedia/commons/5/5c/Afghanis...