Nuclear Non-Proliferation Treaty:
It allows only nuclear weapon states to have nuclear weapons and stops others from acquiring them. A nuclear weapon state is one which had manufactured and exploded nuclear explosive devices prior to 1 January, 1967. So there are five nuclear weapon states: US, USSR, Britain, France and China.
A non-aligned posture also served India’s interests very directly as well as India intervened in world affairs to soften cold war rivalries by reducing differences between the alliances and from escalating into a full scale war. Though India’s policy of non-alignment was criticised on a number of counts: