You can start to see how far-reaching American sanctions are. A British bank is being told that it cannot do business with a Chinese company, because that Chinese company allegedly controls a Hong Kong company that imported small numbers of American goods into Iran. As I understand it, these sorts of extensive secondary sanctions are not normal, and are a sore point between the US and many countries, including some of its allies (such as France and Germany).

I would be very interested to know what gives the US any jurisdiction to demand the arrest of a foreign executive on foreign territory, for acts committed on foreign territory. Whatever the legal justification, though, this is a very unusual and aggressive step, and one that is transparently motivated by political considerations in the ongoing trade war.