The US is not an empire in the sense that we invade lands to capture and hold them. Our international meddling have had good intentions- I just don't think they have worked well.
As for China- I don't see how it make sense for them to attack or invade the US. They already benefit greatly from us economically- why would they want to kill their golden goose? Furthermore, even with modern transportation, the logistic problems of managing land on the other side of the world would be enormous. It doesn't make economic sense. China may well do some land grabs in the future- but it will be in their own area where their acquisitions can be easily managed.
In any case, our immediate problem is the middle-east- not China- we have got to break our dependence on foreign oil- especially middle-east oil- and get our butts out of there. That place is a powder-keg waiting to explode and we should be nowhere around it when it does.
We should now be doing whatever we have to to become self-reliance- as we once were- and not depend on other countries to meet our needs. Then we will have no reason to meddle in their business and create animosity towards us.