It is undeniable that there are the mass of nations have applied mandatory arm duty for men subsequent to their schooling departures. Moreover, for some people this application should be carried out internationally even including women. Personally, I am on the reverse side of this initiative for some reasons.
Firstly, the military duty's primary aim is to ensure national defense and security. If all countries, however, implement it as a compulsory option, they seem be less safe. For instance, Soviet Union residents had to serve military causing the increase of soldiers. By dint of that, european nations joined in the arm race to protect themselves. Hence, there was no party felt secured and the world was always on the edge of global war.
Secondly, the more people serve military, the less workers in labour market are. Meanwhile, state budget has to be used to purchase for relevant equipments. As a consequence, it is likely raise the spectre of economy crisis. Take South Korea for example, government budget has to spend a huge amount ($200 billions) for military purpose per annum even in the recession. Finally, the mandatory military serve makes individual less competitive in their career. To be specific, the period of arm serve lasts at least twelve months mostly without contacting to the contemporary society in which people probably attain experience in work or such thing.
In conclusion, admittedly the national security is of the essence, but the other spheres absolutely worth being considered. Just as i suppose non-arm duty for a more prosperous and peaceful world.