I don't log in much anymore, but when I do, it's to put down lunatics.
Everyone knows that the US drone campaign has the backing of the Pakistani military, even if the PA doesn't admit it and outwardly rejects it.
If the PAF decided to do an areal bombardment of Afghanistan, I have doubts that the US would respond unless US soldiers were killed, which wouldn't happen because PAF would probably alert the NATO nations of the bombardment beforehand. Why do you think the US is forcing the Afghans to sign a BSA that includes a clause that says US involvement in Afghanistan would not including defending Afghanistan in a war against a foreign nation (Pakistan). The US knows that Pakistan isn't Iraq, Iran or Afghanistan.
I know that there is always the chance that NATO would respond against Pakistan if there is any outward aggression from Pakistan against Afghanistan, which is why Pakistan has always should restraint when dealing with the ANA's provocations and Afghan's JCOS' outrageous comments, but none of the NATO nations will risk a war with Pakistan for the sake of keeping Afghanistan safe. Hell, they might even welcome it because it'll might even give them an excuse to get out of Afghanistan.