The electrons which were injected into the radiation belts in 1962 by the United States and the Soviet Union highaltitude nuclear explosions are studied. Data are used from detectors on two low-altitude, near-polar, earth-oriented satellites, 1962 beta epsilon launched in October before the Soviet injections, and 1962 beta omicron launched in November after the Soviet injections. Both flights occurred after Starfish, the U. S. high-altitude nuclear explosion of July 9, 1962. These flights offered the unique opportunity of studying the effects of the Soviet injections on the trapped radiation at low altitudes. In addition to particle injections, particle lifetimes and atmospheric loss mechanisms are studied.