Certainly, one can argue that America is an imperial power. It seems that the US government, especially under the Bush administration, has decided that it must take care of what it perceives as the world's problems. This strikes other nations -- including China, I believe -- as a kind of imperialism.
China has expressed concern over American proposals concerning North Korea and Iran. I presume that China will oppose other moves by the US, especially in regard to Asia. I think that the US must inevitably listen to China, because China is such a large country, in terms of population, military, and economy.