And why should we presume that resource extraction for the purposes of exporting manufactures creates any less a dependency than importing low-cost manufactures for the purpose of consumption?

The stark but useful image is this:  Who has power--the junkie or the drug dealer?

Yeah, I know many Americans would say the junkie, but that is just proof of cluelessness and the whole reason we are now swirling down the shitter.  

isn't creating interdependency relationships the whole purpose of an empire?

No.  The purpose is extracting wealth from conquered regions and colonies.  All national strategists understand this perfectly well.  Usually the wealth extracted is raw materials, but it doesn't have to be.  The main thing is the ability to compel unfavorable terms of trade.  

So:  Is China attached to the US rather than the other way around?  Certainly they are getting unfavorable terms of trade, that is, low prices for the stuff they produce.  But by getting the low prices on industrial goods, rather than raw materials, they have become industrialized--which means materially and technically capable.  

Thus the US is getting immediate benefits (cheap goodies) at Chinese expense, while China is getting the long term benefit of economic strength and capability.  Both sides are taking on costs:  for China massive pollution and for the US social breakdown and loss of capability.  

As Chris Cook points out, by September 2007 the US had lost the strategic initiative--the ability to force events rather than be forced by them.  By September 2008 both China and Russia and demonstrated, independently and separately, and in the latter case very publicly, that they could veto US actions in western Asia.  

Thus a relative decline in American power is a two-year-old fact.  An absolute decline is also postulated, on economic and geological grounds.  

The Fates are kind.