I was about to post this.... this is really a necessity....
We must have some nukes in ready to fire mode... our NFU policy makes it must....
Previously our doctrine was we will not use nuclear weapons first but will answer with many folds devastating nuclear attack if some nuclear power nukes India first.....
But that means first wait till some nuclear power nukes you and then you go running towards all facilities from missiles to jets or submarines then bring nuclear warheads at these facilities and then fit them according to the platform which is time consuming and increases the chances of major powers come into action and prevent you from a retaliation....
Why are we spending billions on SSBNs? For the very same purpose.... now since we have 4 ready SSBNs and speed and progress on S5 series is satisfying we have now a confidence to keep 12 nukes in ready to fire mode.... this is a huge deterrence to any nuclear power who doesn't have any NFU type of policy as ones you see nukes deployed on SSBNs in ready to fire mode then it changes all the calculations of the attacking nuclear power....
Below is an interesting video from defense matrix on the same.... as per this video we may have now even touched the number of 200 when it comes to nuclear warheads....
Out of 620 nuclear warheads of China 34 are deployed in ready to fire mode
Out of 200 nuclear warheads of India 12 are deployed in ready to fire mode