> it is doubtful that the US would have the confidence to replace its current high-maintenance weapons stockpile with a new generation of low-maintenance weapons

That's peace time thinking. Little Boy was detonated over Hiroshima without ever having performed a full scale test of the design. Our knowledge and modeling capabilities today are more than sufficient to produce and stockpile a new design that is guaranteed to work -- without testing an actual weapon -- if that somehow became necessary.

There are many reasons why a nuclear power such as the US is unlikely to consider doing this, but lack of confidence in weapon design or manufacture is not among those reasons.