I think to me this is the scariest part. I've seen some information predicting WWIII a couple of years ago and they said it usually takes place when you have a group of super powers instead of 1 and they were talking about how the US power has been slowly falling while the strength of others such as Russia and China were increasing leading to that perfect storm of another World War and a possible new world super power.
RE: WW3 Watch: U.S. Army rapid reaction force in Europe not ready for prime time against Russia