Originally Posted by
Superguy
So yes, they do have control over international travel policies ... at least for US bound flights. Some countries extend that to other non-US flights as well. For example, ICN enforced TSA stupidity for US flag carriers (UA) even if the flight wasn't going to the US - my flight was for ICN-NRT only. It was pretty clear other pax going elsewhere weren't getting the full treatment that my UA boarding pass triggered.
That's not because of ICN. The in-air operation of a flight is governed by the laws of the country to which the aircraft is registered. UA must operate the flight per US law even if it's between two non-US points. I suspect that ICN is enforcing the TSA rules for NRT-bound UA flights per UA's request, since UA probably wants to continue to operate the flights.