The prisoner of war had been tortured for 10 months and beaten repeatedly by his North Vietnamese captors in recent days, and there were threats of more if he did not respond properly when the propaganda broadcast began. Haggard but gritty, Cmdr. Jeremiah A. Denton Jr. slumped in a chair before the television cameras.

Pretending to be blinded by the spotlights, he began blinking — seemingly random spasms and tics. He answered interrogators’ questions with a trace of defiance, knowing he would be beaten again and again, but hoping that America would detect his secret message in Morse code.

To a question about American “war atrocities,” the captured pilot said: “I don’t know what is happening in Vietnam because the only news sources I have are North Vietnamese. But whatever the position of my government is, I believe in it, I support it, and I will support it as long as I live.”

The North Vietnamese, who lost face, were even more outraged when they learned that Commander Denton, in the Japanese-taped interview broadcast on American television on May 17, 1966, had blinked out “T-O-R-T-U-R-E.” It was the first confirmation that American prisoners of war were being subjected to atrocities during the Vietnam War.