America's spooks are about to turn traitor. And one of the few things keeping 'em in line is a set of strongly-worded posters, hanging on spy agencies' walls.

At least, that's the implication from this truly bizarre set of posters, from the Office of the National Counterintelligence Executive. Using the words of Abraham Lincoln, George Washington, and George W. Bush, they remind our spies not to spill secrets – or switch to the other side. Recruiters from Beijing to Moscow to Tehran are, no doubt, cursing the poster-makers' cleverness, and their boundless Illustrator skill. Here are some samples: