What would happen if america tried to take over the world?

Ok so i did a little research, China has WWII wepon's and Russia aint that much better. So heres my main Question what would happen if america tried to take over the world in say 20-30 years or so? america is currently testing out robotics to do some fighting for them, so say we managed to create something like the"terminators" and didn't really have to spend our troops ( or at least not as many and also say we could m produce these warbots) for any fighting would we have a chance at taking over the world?