This is coolbert:
That sinking of the USS Indianapolis at the very end of the Second World War [WW2] almost a thing of legend. Especially with regard to shark attack.
American cruiser having just delivered the components of the atomic bomb to be dropped on Hiroshima while on further mission torpedoed and sent to the bottom in twelve minutes.
Of that crew of about eleven hundred men it is estimated that two hundred killed outright, the rest taking to the water.
Five days later ONLY about three hundred rescued. Two-thirds having perished from a combination of previous wounding, exposure, shark attack.
CONTRARY TO POPULAR BELIEF, A DISTRESS MESSAGE AS ISSUED BY THE INDIANAPOLIS WAS SENT AND RECEIVED. RESCUE VESSELS PROMPTLY DISPATCHED, BUT THEN WITHDRAWN!!
From the book "In Harm's Way" by Doug Stanton:
"XRAY VICTOR MIKE LOVE . . . WE HAVE BEEN HIT BY TORPEDOES, NEED IMMEDIATE ASSISTANCE."
Rescue efforts initiated but then withdrawn. AND NO MORE EFFORT TO CONFIRM OR DENY THE ORIGINAL DISTRESS CALL!! And WHY??
"The prevailing protocol within naval command was that messages that couldn't be confirmed by a reply were to be disregarded as pranks. Such responses were more or less pro forma at this point in the war. The Japanese forces, hoping to confuse U.S. intelligence and draw out search vessels, had made a habit of broadcasting bogus distress signals. Earlier in the war, such a message might have been investigated, but tonight it was written off as a potentially deadly move in the war game."
There it is in the nutshell. An American military prankster sending a false message for "fun" OR the Japanese attempting to entice American naval rescue shipping into an ambush. Such was the thought and not without good reason.