We give China $20 Billion in cash every month (our trade surplus). Other countries give China cash too. This is a big problem for China -- because they are running out of places to put the money. They put some in US Treasuries -- but we pay essentially zero interest, and they already have a trillion dollars of our debt. They put a great deal into domestic projects, but there is a limit to that (inflation). They put another small mountain of cash into pre-purchasing natural resources like oil and copper from other countries, until those prices go up too much and everyone screams.
Now they are building infrastructure projects in other countries as reported in the NY Times.
It should be a priority for us to figure out how to stop giving them all this cash.