linchpin

Tho other day I was watching a show called Castle, and there was a plotline about someone identifying an event or a person who could start WWIII, a war America couldn't win, at the end of which we'd surrender.  The linchpin turned out to be the daughter of a Chinese businessman.  I won't go into details, but the story's so plausible it's a little scary.  And it makes me wonder about the kinds of changes set in motion by Facebook and Twitter: spheres of influence that supercede boundaries.