Australia

For perspective: America has what's known as the "Selective Service System" where it's compulsory for every male citizen to register within a month of their 18th birthday for potential conscription. Now, Trump is considering on making the process automatic by December.

In their case, the current system works under mandatory registration which isn't automated. Not only does it apply to citizens, but also residents, aslyum seekers and immigrants. Now, imagine the same thing happening in Australia, would it be supported or opposed?

Like this: the Australian government in Canberra refers from the database on where every Australian male possesses state photo ID, driver's license or passport (all states and territories) by putting their name onto a draft lottery (the registration process for conscription has been automated).

It would mean, in some time: you can be called up by the ADF saying you have to serve when the circumstances deem it necessary (and failing to comply results in imprisonment) and they are not excluding male Aboriginal & Torres Strait Islanders from the draft (making it mandatory to serve).