The bad news had been labeled "Top Secret" but it had leaked out. One leak was Colorado's Senator Edwin C. Johnson, member of the Congressional Joint Committee on Atomic Energy, who unwarily blurted it out on a television program in an argument for tighter security regulations. The news: the Russian atomic bomb contained plutonium.
U.S. Intelligence, scientists guessed, must have collected an appreciable quantity of radioactive dust thrown up to the stratosphere by the U.S.S.R.'s bomb blast revealed last September. The two fissionable materials, uranium 235 and plutonium, leave different residues. If enough...