Great writing, and a lovely, fast-paced thriller. Wish there had been more on the Pathfinders and their action deep in enemy territory - hope you will expand this when you get to later drafts.
However, I'd like to understand why you've left the rest of the world out of both scenarios - do you believe that in a three-cornered, nuclear-armed conflict zone, the US in particular, and possibly Russia as well, will not get involved? At the end of the previous scenario, I would've imagined a vast change in China's relationship with the rest of the world (either ostracism or fawning), and even more so in this scenario. Given that things went nuclear already at the beginning of the scenario, I can't believe that the rest of the world (again, read the US particularly) would not have tried to step in. No matter what the speed of our response, there would've been US missiles aimed at both Indian and Pakistan, a "take the sharp toys out of the playground" strike, or a very, very panicky and quick response to try and secure Paki nukes. Nor would, I imagine, the Middle Eastern countries stay so calm: either they would've fallen sharply on the Islamic-republic side, or remembered which side their bread was buttered - a nuclear-wasteland in South Asia is in no one's interests. I can't even imagine Russia staying out of this just to needle the West: this isn't Syria, and the Russians aren't mad. What I'd like to see is India, China and the USA rushing to lock down Pakistani nukes, with a couple of subtle words exchanged between the USA, Russia and China to keep their own nukes out of this, but who knows? All I know is, no one's going to allow two 'small' nuclear powers to go at it.
Frankly, even the idea that a nuclear attack on Mumbai would NOT be blamed on Pakistan is far-fetched - it's not like there are too many supermarkets for nuclear warheads. Even if the response from the 'global community' is not direct punishment against Pakistan, the knowledge that a (most likely Pakistani) nuke has made its way into terrorist hands will mean that no one's going to wait to find out whether the Pakistani government/ISI/army helped or not. Pakistani sovereignty is going to be totally ignored, and NEST/SF type teams, with plenty of cover, are going to be in-country in no time at all.
This isn't meant to be personal
just playing devil's advocate.
One thing that MIGHT be personal, though. I think the ethos attributed to Haider might apply to your thinking: to destroy Pakistan, no matter what the cost to us. Just a thought
I know this is in the end a fantasy, but, well... I know Pakistan isn't going to turn into Canada any time soon, but perhaps there's more than one way to skin a cat, no matter how rabid.