To gain some perspective here, imagine this scenario where Germany was in the US' position and it makes a list of countries: Austria, Belgium, Luxembourg, and Switzerland as nations to exclude from espionage attacks. Imagine that we are in a military alliance with them (NATO) and Germany has military bases spread across the US.
Would that not make you feel uneasy to suddenly learn one day that not only you are a possible military target but also that you are an active espionage target? How can you trust someone who does not trust you and feels the need to spy on everything you do and every word you say?