If Ukrainians wanted they could have prevented this at the time of Soviet Union dissolution, but they didn't so there's not much to discuss.
My point is basically that if Ukraine tried to take full control of the Nukes in their country, they would have been picking a fight with Russia, and possibly the US as well.
https://www.washingtonpost.com/archive/politics/1992/03/14/u...
https://www.jstor.org/stable/resrep10926.13?seq=2#metadata_i...
If Ukrainians wanted they could have prevented this at the time of Soviet Union dissolution, but they didn't so there's not much to discuss.