ICBM? For who?
You've already got India covered. I mean you can go and make ICBM and piss the world off in the process.
Let's hypothetically say Pakistan somehow managed to develop ICBM but then what? Do you think Washington would care? Even if you attack first they've got ABM [Anti-Ballistic missile technology]. Plus you can never win a war with US of A using conventional methods. I personally think Pakistan should concentrate on Economy rather than Arm race.
This way you're just helping India and leading your country in the wrong direction.