The idea of a device which has an arbitrarily large number of Teller-Ulam stages, with each driving a larger radiation-driven implosion than the preceding stage, is frequently suggested,[REF][REF] but technically disputed [REF].
According to George Lemmer's 1967 Air Force and Strategic Deterrence 1951-1960 paper, in 1957, LANL stated that a 1000 megaton warhead could be built [REF].