I am only discussing Japan and Japan has no external debt. You WRONGLY claimed it did. Now you are bringing Japan's and Germany's public debt into the picture. That's a different subject.
You are the one who is very loudly confusing public debt with external debt. I suggest you consult wikipedia to learn the difference
The CIA Fact Book says they had about $1.6 trillion in external debt for 2004. That number will be larger today. Source
Nevertheless, my point had to do with their total public debt. It's 170% of GDP. Much higher than ours. For a country that does the only thing you claim they need to do to remain healthy - maintain a trade surplus - they sure don't look healthy from this perspective. It's all about debt, right?
So the point remains the same, how can these countries have larger public debts than we have, as a % of GDP, when they run massive trade surpluses? With these huge trade surpluses why has Japan's economy been mired in recession and deflation for 15 of the past 16 years? Why has Germany experienced little economic growth and incredible unemployment? When was the last time we had 12% unemployment or 10 years of deflation?
Conversely, The US, with it's massive current account deficit hums along as the locomotive for the world economy, sporting the worlds largest GDP (more than double Japan) and growing at a rate that makes us the envy of the world. How do we maintain such a low rate of unemployment, a rapidly increasing personal net worth, a manufacturing sector that has expanded for 37 months in a row while fighting a war and dealing with the highest oil prices in history?
How do we do it if the trade deficit, which we've run for more than 30 years now, is so detrimental to our economy? Or, maybe you're just wrong.