The risk is not from US Sovereign Debt, the risk is not from 'bond vigilantes', the risk is not from relying on the 'kindness of strangers' to 'finance' the US. There are no US Government Bond Market 'Vigilantes', nor is the US Government 'financed' by anybody, it is the sole issuer of the US Dollar and is the source of all Dollars in existence.
So what are the real risks? This is one:
Meanwhile, the 1% running the US looks to be trying to take the lead in the global austerity race to the bottom as the Democrats in the super committee on deficit reduction have led off by proposing a $4 trillion deficit reduction package.
With the US consumer still in the middle of a balance sheet recession, and the Financial Sector still posing a risk to economic stability, and with the US economy having >9% unemployment and >35% labor under-utilization, and with inflation being moderate (and most of that is producer constrained cost-push inflation) and not even remotely demand-pull, we have no issue with the economy 'overheating'. We have a massive problem of deficient demand, and a $4 Trillion deficit reduction will be $4 Trillion sucked out of an economy when demand is already far too low.
Those who seek to massively cut the deficit (or worse, balance the budget) in the name of 'avoiding a Depression' will be the ones to cause it.
If this austerity effort makes serious headway, like I said here and here, then my sideways 'muddle-though' secular bear market projection becomes much less likely and something far more dramatic and bearish starts becoming probable.