Again, I don't know whether such a program exists or not, nor do I know the strategic implications. All I'm talking about is capability of having such a system in place.
If such a program exists, is it a tit for tat measure? I don't think so, Pakistan has no desire for a 1:1 capability, as it knows this is an impossibility. It's more to do with not being left technologically behind by India and geopolitical implications rather than it is about actual strategic motivations.
It's kind of like nuclear weapons. India and Pakistan will never likely use them, but they can have bragging rights about having them. It's the same reason why India developed an pseudo-ICBM (Agni-V), they just want to show they have somewhat of a long range firing capability, even though the only likely enemies they face are in their immediate neighborhood.