Here’s the total amount of US debt owned by foreign governments. They own about 25% of the total $10 trillion dollar debt. Here’s a breakdown of ownership of all the debt (doc) over the last 10 years. Right now China owns a mere 7% of the total US national debt. In fact, investors are withdrawing their money from markets around the world and stuffing them into US Treasuries, which are perceived to be the safest place for money right now. From June’07 to June’08, foreigners bought ~$450B more and US mutual funds added ~$200B of US debt. Remember this the next time a politician stirs up nationalism and racism by complaining that China owns the US. Here’s a good source for more info on the debt.