Development of the new warhead, the first in two decades, could have "international impacts" if critics view it as a new weapon rather than a replacement for the ageing stockpile, said the scientists, headed by Bruce Tarter, a former director of the Lawrence Livermore National Laboratory, and including two other former directors of the US government’s nuclear weapons research laboratories.
Some countries could see the warhead "as contrary to both the spirit and letter" of the Nuclear Proliferation Treaty "unless explicit and credible efforts to counter such assertions are made," said the panel, which was convened by the American Association for the Advancement of Science to study the warhead plan.
The scientists also said it is impossible to estimate the cost of modernisation plan. The administration argues the new warhead is needed because of concerns about maintenance and future reliability of the existing warheads. The administration is asking for $89 million (£45 million) to proceed with a design plan and draw up a detailed cost estimate over the next year.