'We could not understand why they kept coming but they did.'
The reason, it turned out, was drugs: these "holy warriors" are taking drugs to get high before attacks. It true, as we pushed into the town in April many Marines came across drug paraphernalia (mostly heroin). Recently, we have gotten evidence of them using another drug BZ that makes them high and very aggressive.
BZ is not your typical substance of abuse. It's a hallucinogenic chemical weapon."
-- Defense Tech: Insurgents Using Chem Weapons - On Themselves?