Originally Posted by
SFO777
Pretty sure that there are different rules for GUM since it is just a territory... you even need to clear CBP/customs flying GUM-HNL. A friend has an offices in LA and Guam and transits NRT regularly on a GUM-NRT-LAX routing, both same and separate tickets. Just because UA will sell you a ticket does not mean that they will let you fly the routing... unless you can legally enter Japan. You risk being denied boarding at your outbound US gateway either because you can legally enter Japan or cabotage. But if you decide to go for it, good luck. You may or may not one successful, but I'd recommend having a plan B.
From up thread....
https://www.flyertalk.com/forum/33086865-post79.html
Good to know with GUM-HNL. Good point, I've seen sales for connections domestically within Japan which are not allowed coming from an international flight. As travel ready center is green and hypothetically I can get mobile boarding passes..... would the boarding denial just be at the gate to Japan? Have seen past threads of folks doing NRT turnarounds/back to mainland US... but that is in non-covid times of course - we will see!