Saint Benedict Catholic Formation

Hey y'all i'm back! 
I wanted to bring up a quick subject from the Avoiding War discussion from the CCC last week.
It's from paragraph 2310: "Public authorities, in this case, have the right and duty to impose on citizens the obligations necessary for national defense."
So, that being said, does the government have a right to draft soldiers (i.e. WWI + WWII et all) for a war overseas, assuming the war is a just one? What about if it is not?
And do the "obligations necessary for national defense" apply to all citizens, male and female, and old and young? This paragraph seems very vague to me.