wrong. back when the ussr was still a thing the dprk had a pace of development matching, or in parts even exceeding that of the south, and that even with only minimal soviet assistance post 1965, as korea stayed neutral in the sino-soviet split.

the prc on the other hand not only complies with the sanctions that were unjustly imposed on the dprk, but was instrumental in bringing them about in the first place. the reason for this is that china, since dengs betrayal of socialism, tries to integrate with the western dominated world market, something an extremely belligerent anti western dprk is not useful for. this is why the dprk currently tries to develop ties with bourgeois russia, as they are at least somewhat serious about fighting the west.