A special forces soldier told me once that they always carry with them their helmets. They just don't wear them because of the way they operate. They usually keep them in their backpacks because when they have to reach a target via land infiltration, they have to move great distances and pass unnoticed. read more
With any of the special forces of various militaries of the world, helmets are worn when they’re an asset and not worn when they’re a liability. There is some weight and bulk to a combat helmet, and this can be a hindrance to light infantry, which special forces essentially is. read more