To be fair, changing your interest rates directly changes spot and futures rates compared to all other currencies, it's a purely mechanical relationship. So every time the fed changes interest rates they're manipulating the USD rates. And while fighting a trade war or specifically devaluing the dollar isn't their primary goal when changing rates, they're fully aware of the impacts it will have in those areas, among others, and take that into account when making their decision. I'm sure we could find some old fed minutes where balance of trade was discussed vis-a-vis rates. Obviously you and I who are into the minutia of this would say it's different then the Chinese govt doing it, but from their perspective and that of most of the world including most Americans who don't understand our financial system...it's pretty much the same.