Being the most powerful economy in the world is the only thing that has made the current $3 trillion foreign debt possible, if that increases to 15 trillion in the next 10 years, how long do you think China is gonna count on getting it's money back at some point? What happens if China, Japan and/or the Saudis decide ok that's it, no more bonds for us? I don't think it's pessimistic to say the situation is slightly risky.

http://www.treas.gov/tic/mfh.txt