Why Destructive weapons?

Each and every nation spends lotz n lotz of money in the research field . Ya when you take a serious note of it you could find that many researchs are going on building weapons . Its to make their army stronger. When you consider it as to strenghen the army then the real fact is that they(the country) has no thrust on their neighbouring countries or the remaining countries of the world. Whats the need to strengthen the army?? If the nation tries to terminate the terrorists its better each and every nation can join hands to do that job. Everyone may know that it would be easier to eradicate terrorism as a group than as single.

There are certain rules that atombombs are violated and when you see they put a large amount on that . Is it for pride and prestige . You are not going to use that as a weapon for sure and some nations have even signed an agreement that they will never do . Then whats the use in having it. And why that much researches.. To me its just a waste of time .. Everyone needs a peacefull world without war but the individual nations will manufacture weapons and the destructive things. IS the words they say are true from their heart . My guess is that each and every nation wants to rule the world . If at all a planet with living beings is discovered and there comes a war between them and our world there wont be peace filled in the whole world.