Ordinary fission bombs can be made powerful enough.
Even then Teller was fixated on building a hydrogen bomb and would not do the work of the laboratory that Oppenheimer was directing, which was trying to build a fission bomb. Teller was a witness--a hostile witness--and his testimony was devastating.
Paul Ehrlich, one of the loudest and most influential voices in the movement, proclaims in his textbook-like Ecoscience, "The knowledge needed to construct fission bombs ...
Taylor later published a book of his own, in which he further elaborated on the simplicity of the task: "a few persons, possibly even one person working alone, who possesses about 10 kilograms of plutonium and a substantial amount of chemical high explosive could, within several weeks, design and build a crude fission bomb" (qtd in Cohen 242).
Except for Edward Teller, the General Advisory Committee of the Atomic Energy Committee voted against attempting to develop a hydrogen bomb on the ground that it would be a much less efficient use of fissionable materials than ordinary fission bombs
. But, I said to Rabi, no one had suggested building such bombs regardless of efficiency, only that an attempt be made to see if such bombs were feasible lest the Soviet Union do so.
The Soviets had been working on fission bombs
for years, however, and were clever enough to gain knowledge of some of the American techniques.