First of all as i have noticed most people here really really exaggerate the capabilites of the US and really underestimate of what pakistan can and cannot do. Saying so does not mean that i doubt the US war waging capabilities.
Now lets discuss it hypotheticaly speaking, a possible out come of what would happen if US attacks pakistan or for that matter even if it is possible at the first place?
I'm gonna answer the last part of my hypothesis first is it even possible for the US to attack pakistan, the reply is No, reason is the US economy and the state it is now and will be if US attacks pakistan. Not only will the US economy bankrupt, but so will the world economy, considering the impact that this conflict will have on the oil prices.
Now lets talk militarly. Pakistan military is no push over. Its the world's seventh largest military and when it comes down to conventional warfare and boots on the ground, they are considered one of the best in the business if not the best. Mr Salim can provided better insight on this since he can explain Pakistan army from a third person's point of view being an Ex-indian army officer.
Moreover pakistan army has two professional wings to support, i.e the airforce and the navy. Now in no way are these two comparable to what the US have however one thing that most people here forget is that whether it these units are big or not, you will have to neturalize them inorder to destroy the military war machine of the PA. And let me assure you that it will not be piece of cake for the US. Allow me to expalin why, the reason is unlike in the gulf wars and then again in operation iraqi freedom, USAF encountered nothing. It was a walk in the park destroying targets at ground, i remember watching an interview of a US pilot of the F-18 saying that once in iraq far he was chasing and iraqi mig and while he was chasing, he never noticed another mig right at his 9 o clock( i'm not sure about the exact clock that he mentioned) and said that if he had fired, i would have never survived, what happened instead he choose not to engage it and flew away, the US pilot shot down the mig he was chasing and then went on to shoot down that mig which just flew away and so he shot both. The point is that there was no resistance at all and so maintaing an air superiority over iraq and destroying a few old Russian SAM sites was no big deal. But this ant gonna happen when you will come up against PAF. PAF be small in numbers is a very professional force and it will sure take the gutts out of the USAF before US could neturalize it to maintain complete air superiority over pakistan.
Another threat that the US will face will be from the pakistan's ballistic and cruise missiles. Now a question here how many US soilders died during the first gulf war when an iraqi scud missils hit a US barrack in Saudi Arabia. Compare that to the modern pakistan's missile systems and you can calculate the amount of damage that they can cause and the amount of US and allied casualties in afghainstan. I'm sure US will not risk the lives of so many americans just to prove a point.
Third read about the high altitude mountain warfare and its impact or that either it is possible for the US to gain results in such mountaineous areas and that too when they are up against not only the tailbans and balochis but also against the whole pakistan army, its not hard for one to imagine results. Tango the last part is for you because you seemed very much confident in predicting the outcome of war or that a conventional conflict will be short. No my friend, you dont know pakistanies that well, the pakistan army is trained on the basis of taking out a much superior enemy both in numbers and technology i.e the indian army, and when it comes to the survival of pakistan, let me assure you that PA will defend it to last blood of each and every solider.
Last but not the leat, certainly we have the nuclear factor and as mentioned in our nuclear doctrine, if a large part of pakistani terrority is been taken over or a large part of pakistan armed forces is destroyed, we will go nuclear. A nuclear strike on afghanistan, and the out come can be predicted. Obiviously we too will get destroyed in the retaliation strike carried out by the US but the point that i am trying to make is that in no manner this is possible even in the slighest of manner for the US to attack directly on pakistan the way it did on iraq and afghanistan. There will be too much at stake for the US, most importanly the loss of US lives on a foregin soil as a direct result of this conflict. US government will never ever be able to justify it to the US people.
In my opinion as a 60 year old country Pakistan has a REALLY good success,but agianst USA...i think usa would have a hard time. they might defeat our navy but our army and AF i doubt
