Strange that the Manhattan Project went from a "colossal blunder" to a
succcess in a small number of days, however it took the "Basic High
Explosive Research" group from June 1947 to October 1952 to create a
non-US implosion device ...

Do you know how long did it take to complete non-US aircraft carrier HMS Ark
Royal even though her builders were extremely experienced and knowledgeable?

Maybe they should have imported the complete management team from Japan.