No, it doesn’t. A memorandum does not have a force of a treaty. Furthermore, the Budapest memo was very clear that we were not supposed to assert our dominance there either. More importantly the government of Ukraine that was party to that was dissolved in 2014 when it was overthrown by a Nazi putsch.
Last but not least, when the Nazi forces from western Ukraine attacked Russian speakers in the east to bring them under the control of the coup government, under United Nations rules, Russia was free to act. Duty to protect.
Russia has the same legitimacy for her military action that ours did in Syria does, that ours in Kosovo did, or ours in Libya did.
Kinda lost you when you said the Nazi part. 🤔