@cicerone imposter,
Holders of US bonds are worried, but there's not much they can do. They worry that once people start to dump bonds, the prices will drop, but there's nothing in place of US treasuries where one can put their money. The options are few, and there really aren't much in terms of safe-havens in Europe or Asia.
Europe is struggling with Greece, Ireland, and Portugal. In Asia, the Chinese and Japanese hold US Treasuries, but they have nowhere else to invest.
China is looking at inflation and a slow-down in their economy.
What to do.