If that german citizen stepped foot in the USA, they might get arrest for espionage. But I highly doubt a German court/judge is going to approve an arrest warra

If that german citizen stepped foot in the USA, they might get arrest for espionage. But I highly doubt a German court/judge is going to approve an arrest warrant for a presumably sanctioned activity. Now, if a private german citizen wiretapped the USA's president's phone for the lulz then yeah they might get arrested and extradited. Whether or not something is illegal is in the eye of the beholder and IIUC, Title 50 Section 36 explicitly makes espionage legal [1] (when done by the US against other people). [1]: https://uscode.house.gov/view.xhtml?path=/prelim@title50/chapter36&edition=prelim https://uscode.house.gov/view.xhtml?path=/prelim@title50/cha...