“Why would the Pakis wish to do such a thing to their friend and neighbor China?”
Islam has no friends. It uses people and cultures until it can betray them and eliminate them. China has been idiotic in taking them at face value. (Or, perhaps they think they can play with fire and not get burned.)
Do you really think the Paki government would not know about, or would remain quiet about a 777 full of Chinese nationals landing on one of its airfields?
We took them at face value for a long time too... and yeah, good point - we got burned.