US Attack on Pak Soldiers & Iran Downing Drone Explained

The US was disappointed that there was a lull in the Pakistani attacks on the Taliban. Also the US was disappointed that Iran no longer supported its presence in Iraq. The Pakistani soldiers were attacked in expectation that Pakistan would back down and also stop the flow of sophisticated weapons that have recently started up from Iran to the Taliban.
In the event the calculation backfired with the Pakistani population overwhelmingly angry at the US, eventhough their country is virtually destitute from the 10 year support it has offered the US in its war on terror. The brotherly ties between Zardari and Ahmadinejad are strengthened and explained in this video.
The US can no longer survive in Afghanistan without support from either Pakistan or Iran. Source