Indeed, there could have been some other critical shortage barring the way. (IIRC the soviet bomb-makers mined half their uranium in germany, but something else

Indeed, there could have been some other critical shortage barring the way. (IIRC the soviet bomb-makers mined half their uranium in germany, but something else maybe.) But aggregate industrial capacity wasn't obviously a show-stopper, if they were able to fund another very high-tech high-cost project.