You can not imagine the loss of humanities in the world. How and by whom this may be triggered. Some video links are available below.
The world is very big. Thousands of years ago people use to travel either on foot or take help of animals like Horse, Elephant to drive carts. There used to be many small and big kingdoms whose rulers were keen on expanding their wealth and prosperity by fighting among themselves. In such wars only those got killed who directly took part in the battles. Natural instinct like anger coupled with the availability of weapons of mass destruction have made it possible for nations to destroy each other or even the complete world. If we can communicate with anyone in any nook and corner of the world within seconds why not we think on a new world order of No Wars between Nations.