in my opinion, there is a big politics behind it. Pakistan is feeding and breeding terrorist. There is a possibilities that China is playing proxy game, backing Pakistan to create terrorist so that they can become obstacle in American aggression. How 26/11 mastermind Hafiz Sahid is moving freely in pakistan? Pakistan officially helping and funding terrorist organisation. It can not be ruled out that Pakistan has secretly handed over nuclear formula to Al Quaeda. If they do so, Pakistan will be the first target. Like Belochistan, terrorist will first target to Pakistan provinces and Pakistan government is aware this fact. 

If America do not take control over Pakistan's nuclear arsenal, in future, there will be a nuclear attack backing by Pakistan government, similar to Mumbai attack. It may take place to America, England, India or any other country. India is not safe enough from any future attack backed by Pakistan government. At present, no one thinking about terrorist attack but people of India are busy enough to fight against corruption. 

Pakistan is trying to improve relationship with India as US is a biggest threat at present to them. So for their own interest, they will try to improve ties of both the neighbouring country. And if they fail to do so, I think there will be a worst situation in the world.