India has detonated nuclear devices , first in 1974 and again in 1998 . India is estimated to have enough fissile material for more than 150 warheads . India was among the few countries to have a no first use policy , a pledge not to use nuclear weapons unless first attacked by an adversary using nuclear weapons , however India 's former NSA Shivshankar Menon signaled '' a significant shift from " no first use " to " no first use against non-nuclear weapon states " '' in a speech on the occasion of Golden Jubilee celebrations of the National Defence College in New Delhi on 21 October 2010 , a doctrine Menon said reflected India 's " strategic culture , with its emphasis on minimal deterrence "
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Pokhran-II
Treaty on the Non-Proliferation of Nuclear Weapons