A world war would not be good for any nation state. It would likely bankrupt the dollar, as the opponents to the US would dump the Federal Reserve Note as an act of war. If the opponent were a BRIC nation, the amount of dollars dropped would kill the dollar's ability to trade on the open market. The other thing a country could do is set off a couple dirty bombs in the US over a span of 10-20 years, but each time there is going to be a "terrorist" attack the Police State is going to tighten its grip. It will not be long until the Police State goes for broke. They tried their hardest to capitalize on the AZ shooting, imagine what would happen if there were another major "terrorist" event. Our Navy would lock down the Pacific and Atlantic. But I do not think we would win any wars abroad. Our Special Ops may be the best, but in order to defeat China/Russia/Iran on THEIR soil, we would need to nuke them. I do not think the US will use a nuke anytime soon. Besides, if they do, then the debt problem will turn into WW III.
The US debt is a big problem. If the dollar can not buy oil from abroad, we will need to tap more oil here. That would raise the cost and thus raise the price of oil. It would kill the economy. I do not think any wars will start in '11. Maybe a war between the Koreas starts in '12 and develops into a WW III type affair.
China has decent technology, a huge army, and a decent navy. I think that they are no better than France, but with a few more tools.
The bomb in Russia is another blow to freedom around the world. What if Russia and China began to have problems controlling the opposition to their fascist regimes? What if the Chinese peasants rose up? There are tens of millions of Chinese that strongly and vehemently oppose their ruling party.
I bring this up because African governments are turning over like bacon on a skillet. Tunisia has had three presidents this week, Egypt is missing tonnes of gold from their vault (thought stolen by their President), and no Albania is in a state of turmoil. Ireland's President stepped down before the election, Iceland is going ahead with bankruptcy, and Europe is protesting austerity. America watches from the backseat. What will happen next?
I think that the US could pull back all its troops and guard the oceans, and we would be safe. Our air force and navy can watch our parameter just fine. I would only be worried about China if our government went to war there. That would be a disaster because the dollar could not fund the war effort. The Nazis lost WW II for the reason that they did not have the oil to power their army. They tried to turn coal to liquid. This process is not energy efficient. The US could try to tap the Bakken formation full throttle, but it would devastate the natural landscape. There would be no winners in WW III.