Why did the European countries start to increase weapons and ammunitions?

1)       The belief that only militarily powerful nations could retain their supremacy in European politics led to the rose of militarism.
2)       The European nations, started increasing their military strength to outwit (take the better off) each other in the race of expansion.
3)       Large number of new destructive weapons, warships, tanks came to be manufactured.
4)       Every European nation argued that this vast arms accumulation was only for the safety and not for war.

5)       Yet, the storage of large amount of arms and ammunitions made the situation in Europe explosive (unstable).