Although the weapons used in the K Project were much smaller ( up to 300 kilotons ) than the United States Starfish Prime test of 1962 , the damage caused by the resulting EMP was much greater because the K Project tests were done over a large populated land mass , and at a location where the Earth 's magnetic field was greater . After the collapse of the Soviet Union , the level of this damage was communicated informally to scientists in the United States
Starfish Prime
Starfish Prime
Soviet Project K nuclear tests