"Starfish Prime was a high-altitude nuclear test conducted by the United States, a joint effort of the Atomic Energy Commission (AEC) and the Defense Atomic Support Agency. It was launched from Johnston Atoll on July 9, 1962, and was the largest nuclear test conducted in outer space, and one of five conducted by the US in space."
"... these man-made radiation belts eventually caused six or more satellites to fail ..."
(9 satellite failed in total)
~~"Estimates for (...) excess deaths (...) have likely amounted to between 10,000 and 100,000."~~
"Estimates for (...) overall excess death impact of thousands of above-ground tests have likely amounted to between 10,000 and 100,000."
https://en.m.wikipedia.org/wiki/Starfish_Prime