Lol!!!! And what would the UN do? Without an army the UN is nothing. Without countries who act like they care, the UN is nothing. The UN is the biggest waste of money. The UN has no military, but, merely other countries send forces to act as UN Peacekeepers. Do some research man, you'll figure out the UN really has no point, as countries continually violate UN Resolutions and nothing happens to them. Look at Iraq, Saddam continually violated their resolutions, to the point of having sanctions, and members of the Security Council still traded with them. Then, a coutry goes to enforce those Resolutions and suddenly they are war criminals.
There won't be a world war III in our lifetime though if there is, everyone loses but the cockroaches.
I don't know why you guys thinking and arguing about something like this... This not some middle east war, or Pakis killing Indians here.. We talking world war 3 with countries like US, Russia, UK, and China into it, God forbid this would happen there won't be a living there left on earth.
If ww3 happens it will probably catch us by surprise. What we should be worrying about now is those 3 big asteroids that have a chance of hitting earth between 2027 and 2029