1994, Budapest (copied from wikipedia):
According to the memorandum, Russia, the US and the UK confirmed their recognition of Belarus, Kazakhstan and Ukraine becoming parties to the
Treaty on the Non-Proliferation of Nuclear Weapons and effectively abandoning their nuclear arsenal to Russia and that they would:
- Respect Belarusian, Kazakh and Ukrainian independence and sovereignty in the existing borders.[16]
- Refrain from the threat or the use of force against Belarus, Kazakhstan and Ukraine.
- Refrain from using economic pressure on Belarus, Kazakhstan and Ukraine to influence their politics.
- Seek immediate Security Council action to provide assistance to Belarus, Kazakhstan and Ukraine if they "should become a victim of an act of aggression or an object of a threat of aggression in which nuclear weapons are used".
- Refrain from the use of nuclear arms against Belarus, Kazakhstan and Ukraine.
- Consult with one another if questions arise regarding those commitment
With reference to point 1 especially, and points 2 and 3 in reasonable likelihood, remind me again why Ukraine should trust Russia to adhere to their own agreements.