The point of being the guy with the largest stick is primarily that everybody has to do what you say. A secondary function that emerges after you do that is to ensure that those with the smaller sticks don't gang up on you and pay you back. My point is that "defend its interest" isn't it, it's "advance its interest". The US wouldn't be where they are today if there was no military on earth, their huge success is based on the military being there to bully other countries to comply with political demands, or to simply regime change if they don't.

That sure might change, and it won't be pretty for US citizens, but it will be great for plenty of countries. Until they get under China's rule, of course.