Apparently the understanding isn't too deep,
Rod. The US is not only the land of litigation and fines, but the super joker of closing a base to dodge contractural obligations and legal action won't work -- not only can assets be attached and seized (and this is routinely done to lawbreakers of all sorts in the US) but also I suspect even CX would think twice about closing anything when it meant that it could no longer operate in US airports and airspace at all.