This would make excellent material for a McCain ad...if he had any money.
Kruschev thought that Kennedy was a lightweight frat boy who would fold when the Soviets moved missiles into Cuba. (Note to Joe Biden: that perception, and JFK's response, brought us to the brink of all-out nucular war).
The Iranians measured up Jimmy Carter and decided they could take American hostages.
The Soviets measured up Reagan as well. When Reagan fired the air traffic controllers, that sent a pretty strong signal as to the type of man they were dealing with.
Al Queda measured up Bill Clinton, and realized they could do just about anything.
Our enemies don't even have to measure Obama. He's ready to talk when the bullets and missiles are flying.