You are hung up on wrong item and strategy here. The US, without doubt can "make it rain" in terms of expansion of the Pakistani economy through allowing her businesses to invest in Pakistan and allowing Pakistan to trade freely for a while. Just 5 years of such an economic cooperation will set Pakistan up for the future and for the better.
So when you could get investments from the US worth $ 10 / 20 billion a year, and trade opportunities to export to the US worth a few billions a year, do the F-16's still matter? NO, you can use the money you'll make in profits and literally, can start manufacturing a better plane yourself or buy it from the Europeans or others.
For a better future, and for the better good, you gotta look beyond the past and beyond the hurdles. Just because I don't want to discuss a topic with you (referring to the F-16's), doesn't mean I can't benefit you beyond your imagination (referring to the US's ability to help expand Pakistan's economy in literally, no time). You guys need to learn how the real diplomacy is done and how you and others can cooperate for billions, and still keep your interests intact!
Today's world runs on economies, not on F-16's. Your economy is strong, you can buy many F-16's and F-18's on cash!