Crimea was Feb 2014, and then in Jul 2014, Malaysia Airlines flight 17 was shot down by "pro russian separatists" in eastern Ukraine. Seems like they were laying the groundwork for a while. I have no idea what portion of this wikipedia article is true:

https://en.wikipedia.org/wiki/Novorossiya_(confederation)

But it seems Ukraine had questionable control of the eastern parts of the country long before the 2022 "official" invasion.