[Nasrudith]

There is a very legitimate interest in the state banning bribe for international behavior. The US already face accusations of imperialism rightly or wrongly for trade involvement.

While it could be argued as "respectful of local customs/the fault of the host nation" being involved it taints the image of US as a trading partner as a whole and gives a reason for rational actor countries to refuse international businesses from the US for fear they will spread corruption because it worked for them before. By holding them all to the standard of "no bribes ever" it makes it clear that such practices tainting businesses are unacceptable.

If other states are worried about bribery (as opposed to liking it) then it gives them a reason to trust the extranationals - if they report bribery they won't get "Not illegal here" as a reaction but "It is a serious crime thanks for reporting it."

Essentially not doing so could harm the spread of US business which is not good for US economic power from which the rest of the nation's power stems.