The best justification for keeping a large Leviathan is to end conventional war. Essentially, the US can use its military power to make the cost of waging aggressive war against another sovereign state unacceptable. This provides the global public good of security, because when states do not have to defend themselves, or spend funds appeasing dangerous neighbors, they can concentrate on economic growth.
Russia’s invasion of Georgia is a great (perhaps fatal) challenge to America’s role in keeping the peace. By allowing that Saddam Hussein with a slavic name to occupy Georgian territory, we make every state think twice about the “peace” that the world loans us so many billions to uphold:
Signal received, Azerbaijan thinks ahead (Thomas P.M. Barnett :: Weblog)
So yeah, given few to no alternatives, Azerbaijan takes up Gazprom’s offer to buy its natural gas and pipe it westward, possibly killing the planned Nabucco pipeline.
In his Beijing diary, former President (and at the time, de facto US ambassador to China) George H.W. Bush notes how the US failure in Vietnam caused other states to warm up to the Soviet Union and other communist states.
While Communism and the Cold War are dead forever, the inability to expel Russia from Georgia will likewise force countries to further subsidize Gap states such as Russia.
Of course, Russia is in a lot of trouble regardless. Russia’s economy is caving in, and Putin’s nemesis George Soros is influential with the incoming government of the United States. Still, the U.S. is expected to supply security, and so far in Georgia it has been unable to do that.
That is what we see in Azerbaijan’s actions, and it is harmful to us, to the world, and to peace.