How did America dominate the world?

i don't think china can replace america as a superpower yes they are on the verge to be a superpower and they had a lot of humans....but america keeps peace in the world ..what would happen if the soviet union dominates the world ..i mean china and the rest of the world will be in the command of the soviet union because they were a communist country at the time...and also one more thing we americans or i would say we US governments have the greatest secrets in the whole wide world....you would'nt know because you never served in the military we have secrets that can we americans will be the superpower of the future and our government will never allow our place in the world to replace us