To do that they, the NSA specifically, targets the communications of everyone. It ingests them by default. It collects them in its system and it filters them and it analyses them and it measures them and it stores them for periods of time simply because that's the easiest, most efficient, and most valuable way to achieve these ends. So while they may be intending to target someone associated with a foreign government or someone they suspect of terrorism, they're collecting you're communications to do so.