The Selective Services System here in the US is somewhat similar, though most who register don't actually go into military service. Every male has to register between the ages of 18 and 25 or face prison or a fine. Even conscientious objectors have to register (they submit an exemption claim if they are drafted). Females, of course, do not. It's been that way since the '70s. And we don't have alternative service either: it's either register, or face the penalty.
It's the same way here. Other Christian denominations have to register, though. It just isn't right.