In 1956, the United States launched a series of balloons that took advantage of weather patterns to spy on the USSR. They went up in Europe, glided over the Soviet Union, and were intercepted over Japan, where planes would extend hooks to grab the cameras from them in mid-air. What could possibly go wrong?
Still, even the most optimistic assessments admitted that there was a possibility that some of the balloons would veer wildly off course. To aid in recovery, a cartoon and multilingual placard was included, encouraging them to be brought to U.S.-allied bases for a reward.
“THIS BOX CAME FROM THE SKY
IT IS HARMLESS
IT HAS WEATHER DATA IN IT
NOTIFY THE AUTHORITIES
YOU WILL RECEIVE A REWARD IF YOU
TURN IT IN AS IT IS”
And if the Air Force thought that the Soviets wouldn't notice the balloons, they were sorely mistaken. Read about Project Moby Dick at Atlas Obscura.