David Ignatius

2011 is one of those years that historians are likely to look back on as a 'hinge.' And the truth, at once frightening and exhilarating, is that we don't know yet which way the door will swing.

U.S. adversaries exploit power gaps. It's easier for Russia to invade Ukraine with irregular forces out of uniform, the so-called 'little green men,' than to send a conventional army that would challenge NATO.