Jamie Galbraith's clearly shows that fears of an American default are exaggerated. He says:
Let's suppose that the Treasury actually says to the People's Bank of China, sorry, we can't write a check to you right now. Well, in the case of the People's Bank of China, the bond that they hold would become a defaulted bond, but it would still be there. And the Treasury would still recognize its obligation on that bond and would presumably be willing to pay accrued interest on it. The Treasury would probably say, it's going to be a few days while we resolve this, and the People's Bank of China would, in my view, probably do nothing. If I were sitting in the position of a foreign holder of U.S. Treasury securities in that situation, the last thing I would want would be a panic. I would want this problem to go away.And by the way, Standard & Poor's doesn't matter also.