The U.S. and its Creditors

I found this brief on NPR: U.S. Reverses Course On Who's Top Creditor
It was discovered that China and not Japan is now the U.S's top creditor. Apparently the mistake that placed it in second was due to the fact that China bought many of its bonds through London brokers out of convenience and in order to hide the fact that they have major holdings in a country that they aren't necessarily supposed to support. The commentator states that this can be construed as benign"because we owe them so much it is mutually ensured financial destruction" In other words, China can't attempt anything that would ruin the American economy because that could lead to a lower dollar and therefore less money returned to them. America can't do anything to China because they would call in debts that the U.S government cannot pay. In other words, we're currently in a dead lock.
The earlier reports that Japan was our major debt-holder, were they true, would have been considered an excellent thing for America. We have a better relationship with the democratic, fully capitalist, and less corrupt Japan. Japan also has a service based economy, we don't import as much from them as we do from China. Our political relations with Japan are simpler, and our economic systems are similar, making debt negotiation easier.
The debt-dead lock is quite dangerous, if China faces a sudden upheaval, it will take the U.S with it by cashing in its bonds. The dead-lock also means that it is hard for the United States to make large economic demands on China, like a mass safety screening of all their exports before they head off to the U.S.
I know we've been over debt in class before. I just wanted to highlight that with debt there is always risk. How risky do you see it?