This was not started by Robin Williams. After running a simple Google search for "Robin Williams plan for world peace", up popped:
Urban Legends Reference Pages: Robin Williams' Peace Plan
http://commonsenselogic.blogspot.com...n-is-urban.htm
Robin Williams' peace plan-Fiction!
Regardless of this, I would be interested in why people think that withdrawing all US troops from overseas would lead to world peace (considering that the US foots the majority of Europe's defense bill, to name one example).
But what do I know about the political realm? I didn't graduate from Julliard...