>The NSA's job is to spy on [US] citizens
They're not supposed to (according to for example the Foreign Intelligence Surveillance Act of 1978).
If a US citizen needs to be spied on by the US government, the FBI is supposed to do that.
They're not supposed to (according to for example the Foreign Intelligence Surveillance Act of 1978).
If a US citizen needs to be spied on by the US government, the FBI is supposed to do that.
Semi-autonomous collections systems generally aren't capable of determining citizenship.
Once the data is at rest, much of it is made available to a surprisingly large number of federal and state agencies - and even local agencies via fusion centers, etc.
The system is built for dissemination. Within that, some checks on citizenship could be possible for some data. But even then, once a foreign person is part of the data/comms transaction, all the related data is available - citizenship of the other participants is no barrier.