[dragonwriter]

> Not sure I understand how the military is going to stop individuals from exchanging goods within a country

States stop the exchange of goods within, into, or out of their jurisdiction of types or in manners not sanctioned by the state all the time, it's called “law enforcement”, and either the military or paramilitary police forces or both are often involved in it. It's never airtight, but it doesn't have to be to have a big effect.