Why nations produce weapons of mass destruction which will never be used ? We should struggle for peace.?

It is called policy of 'strategic deterrence'. If a nation has WMDs (Weapons of mass destruction), other nations will be discouraged to start a conflict with such a nation because of the fear that the nation is capable of using such weapons to bring about great amount of destruction. Attaining peace through intimidation.

It's Mutually Assured Destruction. If a country wants to start a war with a nuclear power, the sheer power of nuclear weaponry stops them from doing so as any war would be devastating to them too.

Nuclear weaponry is the reason the Cold War stayed cold. Without nukes there would be many more wars, and nothing to stop new ones arising.

In a world of wolves, sheepdogs and sheep as a sheep, are you not happy that there are sheepdogs with big fangs at the edge of the pasture? Chances are if they are the toughest dogs out there, the wolves will see it is not worth the risk for a little mutton and leave the flock alone. The result, the sheep are safe and the dog never has to fight a wolf....

Its the human condition. Its like playing playstation with one control. If you want someone else to play you have to give them a control. Dick heads run this place.

They build them to maintain the peace.

If you wanna have prace you need to be prepared to war.

Without knowing darkness, there can be no light.