The Russian Non-Invasion Invasion of Ukraine: Expedition?

Now, let us test the definition of "invasion", both practically and historically. First, historically.

During the end of World War I and after the main events of the October Revolution, from 1918 to 1920, the

American Expeditionary Force, Siberia went to the Far East of the Northern Asian continent in order to do two fairly odd things: to secure a railway that was transporting American materiel for the purpose of Russia's self defense during WWI and keep it from falling into the wrong hands, and to rescue a large contingent of Czechoslovakian troops who had undertaken a journey from western Russia to Vladivostok in order to be evacuated all the way around the world via the USA back home in Europe. Very surreal.

 You can read about it on the link but I will summarize briefly below as well.

At that time, Russia did not have control of the area militarily. It was arguably a set of large pieces of territory that may or may not have been actually part of the country of Russia in terms of political, ethnic and linguistic presence. There were armed representatives of various extra-Russian armies, including the British, French and even Japanese. In addition, there was a presence of pro-Bolshevik armed groups as well as a presence of anti-Bolshevik armed groups in the area, plus the stranded Czechoslovakian soldiers who had an entirely different agenda. On top of that, there was a conflict in the objectives and missions between all these groups, even those recently allied in the Great War.

The Czechoslovakian Legions, promised safe passage by the new revolutionary government, were a major force, at least 40-50,000 men. They were pressed at various stops along the way across Russia and they essentially took things into their own hands, somehow putting together an armored train with which they, briefly, conquered large swaths of Siberia, all because of the Bolshevik duplicity in promising to facilitate their safe passage. Ultimately, although basically ruling Vladivostok and most of Kamchatka, the Legions finally cut a deal with the Bolsheviks that included turning over both the leader of the White Russian (anti-Bolshevik) army, Admiral Kolchak and what was just over half a ton of gold bullion that he had amassed as part of a plan to evacuate it further East during WWI. Which is a story in itself.

At any rate, it was mostly a miserable time for the Americans, many fell ill (one was my grandpa) and 189 died from various causes (but not my grandpa) including clashes with various bandit and Bolshevik factions, whom they were not to engage in battle.

BUT, this was called the "American Expeditionary Force". It was an Expedition, not an invasion, even though it involved several large units of armed forces. Because the idea was to reclaim materiel and transport some extra-national troops and leave, it was an "expedition" even though it involved many thousands of troops.

Now, practically: does the Russian Non-Invasion Invasion pass the test of an "Expedition"? Not yet, because they haven't left. They still have time to make it an "Expedition", because they can leave. If they have an Expedition going on, and not an Invasion, then it is still an egregious aggression with real damages done, but something that can be worked out. If it is a matter of holding some territory as hostage, "Ukraine's feet to the fire",  for monies and/or services Russia believes it is due, then this can also be settled in an international court.

But, if they don't state the reason for their Expedition and leave, it can be nothing other than an Invasion.