A British muslim in the Royal Air Force has been successfully prosecuted for going AWOL after claiming he did not want to help kill fellow muslims in Iraq.
It seems to me that an excellent reason for refusing to join a nation’s military is the simple desire to not shoot at, or facilitate shooting at, people that you might not feel should not be shot at. If you have a goodly distrust for the wisdom of the state to begin with, taking the view that you are not going to kill someone just because the government wants you to is a very reasonable default position to adopt.
Now of course all states and their militaries are not the same. If you voluntarily contract to do the bidding of the government of Sweden or the Vatican or Switzerland or Costa Rica or Swaziland or Belize or Luxembourg… nations who are certainly not ‘military extroverts’… then the range of things you could reasonably expect to be asked to do will generally not include going to far off places you had never previously heard of and dropping bombs on the locals.
If you do elect to join a military in circumstances other than fighting off the clear and present danger of an invasion, it seems to me that you are offering to allow the state make the decision for you of when it is appropriate to shoot and at which particular people. Moreover, if you join a military of some place like Britain, France or the USA, i.e. states who frequently sent their soldiers off to kill folks in far off lands for all manner of reasons other than the direct self-defence of the homeland, then it seems a bit rich to take the state’s pay checks for several years but then act surprised if you get asked to, well, help kill folks in far off lands.
Read the damn job description before you take the shilling.