Most NCS action is carried out by through the JCOS with Presidential authorization or through the NSC with Presidential authorization.
Anything can be reasoned as an imminent or actual threat if it puts US interests in danger. This goes for pirates, drug dealers in South and Central America, Asia, and Africa, rogue military folks around the world, etc...
For the stoned kids who chain themselves to trees, there's another world that doesn't play by the "Kumbaya rules". Fortunately, most of these actions are quiet and you don't have to deal with them. The families that remedy these situations don't like it either.