When an airplane stops over in the US, all passengers must alight the aircraft and proceed through US Customs and Border Protection before they're allowed to advance on with the next leg of their journey.
Am I correct to infer that technical stopovers are not allowed in the United States?
Not really an answer, but just a vague data point. I do remember doing a fueling stop in Bangor, Maine on the way from Frankfurt to LA. As far as I remember, we were sequestered in the terminal and not allowed to get out. That was a problem, since they only had vending machines and no way to make change, which was really annoying. However, that was a LONG time ago (when fuel stops were actually still a thing) and I may recollection may not be entirely correct.
