After the end of Second World War balance of power became almost obsolete, and balance of terror came to replace it as a device of maintaining peace. The emergence of nuclear weapons, two super powers, three major nuclear powers, cold war, presence of weapons of mass destruction, and fear of a total war, all combined to produce a balance of terror.
However the balance of terror continued to have a doubtful validity both in the sphere of maintenance of peace and the regulation of the behaviour of states. With fear as its main background factor, balance of terror really failed to perform the function of peace-keeping. It acted more as a source of tensions, fear and distrust and less as a source of peace.
Fortunately now, the humankind has fully realized the dangers of balance of terror. The end of cold war and the emergence of process of close economic cooperation between East and West, have given rise to a positive qualitative change in contemporary international relations.
At present peaceful coexistence, peaceful conflict-resolution and cooperation, and sustainable development through democratization, liberalisation, denuclearization, demilitarization and development are the principles lines upon which the international relations of the 21st century are being developed.