Why dont they destroy Pakistans Nuclear facilities like they did to the other Islamic countries?

Every situation when dealing with islamic countries should be handled differently, every different angle must be taken into account. As far as Pakistan, they currently serve many purposes for the USA: they keep India from getting out of control possibly even becoming a world power, they support us in the war on terror basically letting us do whatever we want in the region, and for the most part are on the bandwagon with whatever the US wants them to do. As long as they play ball with the US, the US will keep Israel from attacking them.