I have posted before that when Japan's economy becomes unmanageable, it will be the canary in the coal mine for the USA. Sure Greece, Ireland, Spain, Portugal, Iceland, and others can be viewed as warnings. But most of those countries have centuries of history of periodic economic resets. Japan however is a different story, it is regarded as a conservative society and as the picture of stability.
So if Japan goes south, America better hear that message.
Yesterday Japan's Sovereign debt was downgraded
Fitch Ratings cut Japan's long-term foreign currency rating by two levels from AA to A plus, the fifth highest investment grade. It cut the more important local currency rating by one notch from AA minus to A plus. Both were given a negative outlook. - Reuters
Japan faces what most western countries face and China faces, a demographic nightmare. See my post "Demographics is driver for economic growth", where I have a couple of odd suggestions on solutions.
There is a strong possibility the deal with China made in 2011 to buy US bonds directly was partially done to prolong America's ability to avoid a bond run. However, I also believe that corruption never wins, and will delay the eventual same result.