Really? The Cold War was hardly binary. One thing that happened is the rise of the rest -- Germany, Japan, and yes, China. Within the victory of the Cold War lies the seed of the ultimate downfall. And you have a funny idea about security -- freedom from being invaded or threatened, not everyone else fork over whatever you wanted for free. Yes, US and its sidekicks are doing a lot of thing that annoys China, but ALL SHORT OF WAR.
And you haven't noticed that US is not in a good place right now. It's inflation is now around 5%. Why does that matter? Because interest rate must follow inflation eventually. And with US national debt of over 100% GDP, every increase of 1% interest rate means at least one percent of GDP of interest payment. If US government's take is about 25% GDP, 5% means 20% of the budget into the interest payment. And there isn't a lot of discretionary budget to begin with, so something is going to give. And you cannot print more money (i.e. QE) either, due to debt limit and that will increase the inflation further. The reason there are inflation is because there is not enough goods for the money that is floating around -- US simply is not producing enough comparing to consumption. And China is actively helping it along by exporting inflation (increase the price in USD) by letting RMB appreciate and canceling export tax rebate. And you are telling me that anyone has the means to drastically increase military spending? Yeah, right.