Here's one idea that needs to be talked about: being a superpower will bankrupt any nation that attempts it.

The Soviet Union's financial demise was proof of concept. The fact that the US didn't collapse in the eighties was due to the superiority of our economic system. It didn't mean that we could continue the effort indefinitely without severe damage and eventual collapse.

Sure, on the surface our economy looks great. However, as you dig deeper the damage become visible. The large budget and trade deficits we have been running since Reagan's defense surge in the 80's have had an impact. Warren Buffett's analysis demonstrates this:

In the late 1970s the trade situation reversed, producing deficits that initially ran about 1% of GDP. That was hardly serious, particularly because net investment income remained positive. Indeed, with the power of compound interest working for us, our net ownership balance hit its high in 1980 at $360 billion.

Since then, however, it's been all downhill, with the pace of decline rapidly accelerating in the past five years. Our annual trade deficit now exceeds 4% of GDP. Equally ominous, the rest of the world owns a staggering $2.5 trillion more of the U.S. than we own of other countries. Some of this $2.5 trillion is invested in claim checks—U.S. bonds, both governmental and private—and some in such assets as property and equity securities.

This loss of ownership has now reached 5% growing at a rate of 1% a year (a rate that will accelerate as the power of compounding interest works against us). The real question for all us is: when will the superpower tax overwhelm us financially and we end up with the same fate as the Soviet Union? [John Robb's Weblog