I think that is just for a show, a deterrent, and a tool to bully other countries that refuse to toe the line. But we see China and Russia have refused to toe the line. That is why these two countries have been made pariah states. As can be seen here in this forum, most people can't see anything good about these two countries. That is because we never hear or see anything good about them in our mainstream media.
Anyway, in a nuclear war, there will be no winner. I am sure US knows that. That is why they avoid getting involved in real battles in Ukraine.
