It seems irrational to do serious harm to an important ally. One might do something weird to achieve a limited, close-in goal, but in the long term the alliance as a whole is threatened, and in addition there is no back-out route. The US is going to be deep in unintended consequences country. And right now, millions of people, some of them very capable, are thinking, "What must I do to deal with this apparently insane entity?" Some of their thoughts -- and actions -- will not be to the advantage of the US.