"(i) the acquisition of the contents of communications transmitted by means of communications used exclusively between or among foreign powers, as defined in section 1801 (a)(1), (2), or (3) of this title; or"
But again , that is gonna mean the law was violated if any of the American citizens was not an agent of a foreign power.
If that American citizen was IN CONTACT with a foreign agent, not an agent of a foreign power.
It doesn't really matter. Citizenship and the rights inherent in it are paramount, and the Constititution is the supreme law of the land. Not to mention that it would be a stretch to call someone cooperating with a foreign power an agent of that power, but that's neither here nor there.
There have been cites listed on FR. One was a mall in Ohio that was targeted and stopped because of the NSA. Another thread was a few days ago but I can't find it. It was a muslim that was arrested for terrorism. The guys name was Imram or some such. (nuts!)