Hmm.. Maybe Each country think they could bring peace to this world, thus improving and upgrading their weaponry to have authority,and thus each other country would improve and upgrade themselves (weaponry), and thus arguments and threats are released within each other, and now we come to what is now called WAR!
War, sad to say is inevitable, but war is always with a cause (But some are senseless), and one cause ironically is to prevent war. Auhm, It seems I'm making a fool of myself here,
well, anyway I hope you get my point.