Difference between 1930s and today is China?

[touchring]

After some readings, I gathered that the real difference between 1930s and today is back then, there wasn't a China that was willing to absorb all the inflation created by the expansionary monetary policies of the US and the UK. So the US and UK had to jack up interest rate and tighten monetary policy to prevent total collapse of their currencies?

Question is, what if China decides to stop buying US debt. What happens then?