India should stop with Agni-5.
And stat concentrating on an impecable missile defence system.
The defence system should be such a way that the incoming missile should be destroyed before entering Indian airspace.
Just to add, DRDO has already said that, with a small technical adjustment, we make ICBMs easily.Agni4 will take care of all our neighbors (no offence meant).
Focus on Naval infrastructure. Strength air bases, ports, coast guards.
Form a Joint force command army, AF, IN (if not already done).