A battlefield ballistic missile is a stupid idea in my opinion. Nuclear Warheads and their delivery systems are STRATEGIC ASSETS that are to be kept under a Centralized Command. A nuclear tipped missile with a range of only 70 km can't be kept under the Central Command.
If such a missile is to be deployed, then it has to be handed over to a formation commander near the border. WHO WILL TAKE THE LAUNCH DECISION If an enemy armored column is advancing? The Head of State, COAS, head of National Command Authority or the Corps Commander??
It is unthinkable that a Corps Commander or a GOC of a Division is to take the decision of using a nuclear weapon!!!!!
Thus only long-range strategic delivery systems are required which offer 2 advantages:
1. They can be deployed from bases which are under direct operational control of the National Command Authority. There would be no need for them to be handed over over to a formation near the border.
2. The launch decision will also be the sole responsibility of the high command.