Ukraine was presented a carrot large enough to go along with it. This has nothing to do with its technical ability, as it remained a spacefaring nation throughout the recession years.

Either way you seem to contradict yourself. On one hand Ukraine, then a major owner of former Soviet military industrial complex could not maintain or use the weapons. On the other you insist unspecified rogue actors would be skilled enough to maintain and use them. Make up your mind.

So the rest of the world did not know anything, as the perfect safety record of enriched nuclear fuel in Ukraine illustrates. They did want for the nukes to end up in Russia for the proliferation fears and convenience of negotiating with one power. The decision turned out ultimately misguided, contributing to the unraveling of the postwar world order we see today (ironically including the proliferation of nuclear technology to the rogue states). Bill Clinton, about as insider as it gets have expressed his regrets about it last year.