If that is the case then how come the US never dared to conduct a single ground operation in Iran? US is a super power above and beyond all other countries combined but does that mean that they want to go to war with each country which challenges their covert operations in that country? The answer is 'NO'.
Raymond Davis is an incident where the US government had to 'negotiate' for the release of their operative who might have had some sort of immunity from prosecution as well, but we will never know because the case was not allowed to go to the court. And his release came after settlement with the aggrieved family under diyat payment (Islamic law) for pardon and not before it! However, it is evidently clear that the GoP is ready to go out of its way to please the US Government and would have let go of R. Davis had he not been caught by the cameras.
The US sent in a NAVY seal team only after Abbottabad was completely surrounded by PakMil under a general undeclared curfew and electricity cut off to the area. The ground reality is that that operation was conducted with the implicit permission and support of PakMil, for God knows what kind of concessions, and against a person who had been dead for the last 8 years or so.
Drone attacks, as has been admitted by many US Government officials, are conducted with the permission of PakMil and GoP. The official condemnation is for internal consumption only and we all know it.
To sum it all up:
1. Can the US go to war with Pakistan: Yes if it absolutely must.
2. Can the US annihilate the Pakistani military structure: Quite possibly, yes.
3. Can the US send in ground forces: It can, yes.
4. Can the US defeat Pakistani ground forces in Pakistan: ABSOLUTELY NOT! And the losses on US side could make the engagement and war unsustainable for the US government. Pakistan may be left as another Afghanistan but there would not be a single base, within Pakistani striking distance, that would be safe and the ground engagement of US forces in guerilla warfare would be catastrophic for the US forces. The political and military consequences would not be in the favour of US. And all this considering that the Chinese continue to sit idle with the possibility of US bases on 2 of her borders!
Who says the US never conducted any operation against Iran? Read about history. From the Iranian revolution to shooting down an Iranian airliner the Americans have been conducting operations. If you are asking why have they not assassinated Ayatollah it is because killing the head of a state without declaring war would be a serious offence even for USA. For all the threats and aggressive postures the Iranians make in their speeches what have they done to hurt America? Absolutely nothing. And USA does not even need to go to war against Pakistan to punish them. Stop the aid and Pakistan is as good as dead.
Raymond Davis was a private security contractor. He had no diplomatic immunity whatsoever. "Negotiations" is diplomatic speak for any threats or arm-twisting made behind close-doors. US just had to demand release and Pakistan obliged. End of story.
Now for the Abottabad raid. The Pakistanis first claim that Osama was not hiding there and the raid never took place. Now you say the raid took place but with active Pakistani support. For argument's sake lets suppose you are right. But this brings up a few uncomfortable questions.
1. Why were jets scrambled to "intercept" US choppers if Pakistani army was actively supporting the operation?
2. Why was the Pakistani doctor arrested and sentenced to 30 years in prison for spying?
3. Why does the Pakistani government vehemently deny any knowledge of such operation? Even the CIA admitted that they kept the operation a secret from the ISI.
If drone raids are good for Pakistan then why is there an "official condemnation for internal consumption"? Why not simply tell the Pakistanis the benefits of foreign drone strikes? Pakistanis world over are protesting against US drone visits and here you are saying that you know the inside truth.
1. Can the US go to war with Pakistan: Anytime they want.
2. Can the US annihilate the Pakistani military structure: In a matter of hours.
3. Can the US send in ground forces: Provided they have a base they certainly can.
4. Can the US defeat Pakistani ground forces in Pakistan: ABSOLUTELY
Please do not mistake fighting counter-insurgency as full scale war. The US army was forced to do police duty in Iraq where in a foreign country they had to identify terrorists from civilian population and arrest, not kill, them. The Iraqi army was destroyed and Baghdad was conquered in hardly 3 weeks.
You think you will get the chance to use your ballistic missiles against USA?
And please don't mention guerrilla warfare. Your dismal record against TTP shows that Pakistan has no clue how to conduct or fight guerrilla war.
Did China lift a finger to help Pakistan during Kargil war? Did China say anything in support of Pakistan during US drone strikes? There are no friends in politics. China is using Pakistan as a weapon against India. Once Pakistan serves its purpose they will dump Pakistan.
America already has bases in South Korea, Philipines,, Japan, Diego Garcia that can suffocate Chinese economy via naval blockade. The Chinese are not fools to risk war with USA over a third country.