which we have already done right? It is rumoured that the K4 has a range of 3500 KM. The problem with SLBMs are that they need to be lighter to be made buoyant. SO they'll have to build a land based one first (probably new propellants, additional work on guidance and control) then test it out, then make improvements to add the buoyancy factor. They'll have to figure a lot of things and I think the land based system will be essential. In any case I don't think this is intended for Pak, this is more for China and to cover the entire mainland.