Boris Yeltsin, President of Russia (left) shakes hands with Leonid Kuchma, President of Ukraine
1996
Image: Oleg Kuvaev's Facebook post
In the 1990's, consensus amongst the world community was that Ukraine no longer needed nuclear weapons as, for one thing, it faced no enemies, and for another, it was not stable and powerful enough to maintain them safely. So a decision was made hat in exchange for security guarantees by Russia, the US and other powers it would transfer its nuclear arsenal - which at the time of the breakup of the Soviet Union in 1991 was quite substantial - to Russia which was viewed as being a more capable custodian for said nuclear arsenal. In 1996, Ukraine dutifully complied to this particular obligation and transferred its nuclear weapons to Russia.
Fast forward roughly 18 years, and Russia started its encroachment into Ukraine by annexing the Crimean Peninsula and sponsoring formation of separating enclaves in the Donetsk and Luhansk oblasts (provinces) of Ukraine. In another 8 years, on 24 February 2022, Russia would start a full scale invasion of Ukraine.
If you need any better proof of futility of good faith diplomacy you are unlikely to find it. Contrary to Francis Fukuyma's thinking the history has not ended and force, or threat of force, is still a tool one needs to ensure one's security - as a citizen or as a state.
References
Ukraine Transfers Its Last Nuclear Warhead to Russia
Los Angeles Times, 2 June 1996
24 April 2022 - Two months into the hot war in Ukraine
@borepstein , 25 April 2022
The End of History and the Last Man (wiki)