The domino "theory" touted so much as justification for the invasion of Vietnam has a fatal flaw .
It assumes dominos stood on end. However the game of dominos is played with the pieces laying flat. And when a player places a double there are three possible moves for the other player at that place.
Think Sarajevo 1914. An assassination of two people brought about so many deaths completely unrelated to that event.
Now we have State Dept. analysts calling for more U.S. involvement in Syria. I assume that Russia and Iran will react negatively. I am certain that there will be more lone wolf attacks in the U.S. against the "war on Islam”.