In my opinion there is nothing called perfect deterrence. A lot depends upon the enemy leadership and many other things. As an example, even in present condition Indian missile and nuclear power is enough to cause heavy damages and no sane political leader (be Chinese or Pakistani) can risk to provoke India for a nuclear strike. But only thing you can’t guarantee whether your opposition is sane or not. The communists in China might not deter from sacrificing millions of their people , leadership in Pakistan might fall in the hand of the extremists who, in their elusion, hardly think of the consequences. A solid air-defense network is what we very urgently require. We are in the process since 1995 and hope in next 5-10 years, inclusion of Akash,SPYDER,Barak etc and ongoing development works with Israel will give us a formidable missile shield (Ballistic or cruise). For last five years there is no news of the ‘Electron Injector’(which could be used to shoot enemy missiles or aircrafts more effectively) that BARC was developing. Hope BARC is on its way to provide us a new generation defense system. Clearly, such a system will act as a solid deterrence as the enemy will be doubtful about the success of their attack. Honestly saying I think Bengalraider has pointed the most important thing- willpower. See, Pakistan with their deterrence of nuclear weapons blatantly supporting anti-Indian activities (they did it even when they didn’t have the deterrence) and India kept on sitting like a duck. Try such tricks against China or US, they won’t hesitate to come and hammer you. Against China, I am doubtful about minimum credible deterrence (what they call it) as they will keep on pushing you as you are not capable of over power him. If you are morally week you won’t be able to hold the ground. You will use your nukes only when they use, but, they will get their job done just by intimidating you. So I think India should try to build more than what is called minimum deterrence and must convey the message, that she is ready to see the end if necessary .