They have mandatory service and many people choose the military service option.
As I understand it, they get basic training and then do annual service. Most people seem to enjoy this as they serve with people from where they grew up and hae a lot of fun (and beer).
Each of these people has a military rifle in their home (and uniform, etc) with live ammo. They are a standing army. A well ordered militia, maybe?
You often see them on the train in fatigues with their weapon on the way to training.