Calling It

when countries build up trade surpluses, this often leads to (asset) inflation. financial institutions sell loans on the basis of inflated asset values, lowering their capital reserve ratios, stretching themselves more thinly, leaving them more vulnerable to interest rate increases.

so in china, here is the situation. they are building up massive reserves. though china is a huge land mass with a huge population, this situation will eventually lead to asset inflation. the banks are becoming more deregulated as we speak.
http://en.wikipedia.org/wiki/Chinese_property_bubble

The idea would be to keep an eye on this bubble. at the point that the government indicates that it feels inflation is happening and raises interest rates, this would set off the chain of events that would prick the bubble, and leave the chinese gov't unable to buy US debt at the same rate. at which point the US would have to tighten its belt for lack of any other option.