http://en.wikipedia.org/wiki/External_debt
External debt is the sum total of nation's trade deficits. Japan does not have an external debt. Our is about 6 trillion. This entry say our external debt is 15 trillion
http://64.233.187.104/search?q=cache:QmhFOHfwPPkJ:en.wikipedia.org/wiki/Economy_of_the_United_States+%22foreigners+are+estimated+at+%2415+trillion%22&hl=en&gl=us&ct=clnk&cd=1
Japan public debt = 170% of 2005 GDP
Germany public debt = 68.1% of 2005 GDP
USA public debt = 64.7% of 2005 GDP
How can it be that Japan and Germany have more debt, as a % of GDP, than we do when they have massive and consistent trade surpluses?