In context, here is a great video from the Belfer center on nuclear bomb making and what are the hard parts [0]. Getting the fission material is the hard part, and in order to get plutonium nukes you need a enrichment plant, i.e. a reactor that is not meant to produce energy but breed plutonium.

[0] https://www.youtube.com/watch?v=zVhQOhxb1Mc (at min 47, he starts talking about the hard parts)