Hand Signals and Eye Blinking.....

Jeremiah Denton who in a 1966 interview, while captive, was compelled to say that conditions for American soldiers were good.

But while saying audibly that everything was fine, he blinked a message in Morse code: “T-O-R-T-U-R-E.” 

In 2004 this soldier was under duress:

And now we have today's signal: