Tyler Cowen worries:
At some sufficiently high debt-GDP ratio, it becomes a foreign policy issue and a big one. Postwar UK had a high debt to GDP ratio, and to this day it is a fine place, but that debt meant the end of England as a world power, for better or worse. The U.S. for instance used financial issues to push England around and they basically had to give up on their overseas commitments. A very high debt ratio here would mean the end of the U.S. as a global world power, again even if GDP does OK. A global power needs the option of spending a lot more, quickly, without asking for anyone's permission. Your mileage on a U.S. retreat from the global policeman role will vary, but it's the elephant in the room which hardly anyone is talking about.
Well, the Dish has been talking about it for a while. It's one other legacy of the Bush-Cheney years: by both bankrupting the country and grinding the US military into the barren dust of Iraq and Afghanistan, those two fools did more to weaken America internationally than any administration in modern times. So much of power lies in the imagination of others. Before Iraq, the US military had immense soft power. After Iraq, where the whole world saw a military incapable of curtailing an insurgency for four years, morally tainted by torture and abuse of prisoners, and now leaving a fractured, fragile tinder box more friendly to Iran than ever before, the deterrent effect has been lost. After Afghanistan, the world has seen the greatest military all but defeated by a bunch of goons and thugs and corrupt election-stealers. A super-power should guard its reputation carefully. Bush recklessly threw that reputation away.
It would not be the first time the desire to project power revealed its limits. Neoconservatism began with a Project For The Next American century. It's achievement is a new century with a newly empowered Iran, Pakistan (the two Islamist states with WMDs) and China. And still they write and act as if nothing - nothing - in their worldview needs changing.