Cool. I believe you have just assembled several reasonable sounding statements into a an inaccurate conclusion. Your conclusion seems to be that you should never truthfully disclose your level of trust or your intentions to an ally. However I believe that conclusion is false.
Countries (and peoples) interests never coincide completely. This is true. But interests are not the primary basis of reliability. The primary basis of reliability is predictability. If you and your ally are predictable, then you can greatly eliminate the need for spying, even as your interests diverge.
So, what level of predictability is necessary before we can say that massive, bulk surveillance of an ally is unnecessary?
There has been a great deal of NSA mission creep. The original mission of the NSA was “No More Pearl Harbors.” We hardly need massive surveillance of England or Germany to know if they are going to launch a surprise military attack. They are stable, democracies. Just reading their newspapers once a month should tell us all we need to know.
It is doubtful that the US needs massive surveillance of any stable democracy to predict or avert a surprise military attack. Stable democracies are predictable that way.
Unstable countries like Pakistan might try anything. They might even give aid and comfort to our greatest enemies. But, I don’t see how telling countries that we believe they are unpredictable is going to make a difference. Making ourselves less predictable by lying seems to be counterproductive. In the long run, it will cause us more problems than it avoids.
The US only needs massive bulk surveillance of England or Germany if we wish to influence or control their populations. The sovereign nations of England and Germany should rightfully consider our surveillance of their populations to be a threat to their sovereignty.
Of course, the current mission of the NSA seems to be: “Never allow a bad thing to happen.” This absurd mission requires absurd levels of spying. Our first step in addressing the absurd spying must be to clearly define and limit the mission of the NSA. Then we can proceed to an effective list of “Thou Shalt Not’s”.
