Much is being made of Ukraine’s incursion into a piece of Russia’s Kursk Oblast as being the first foreign invasion of Russian territory since World War II. That is, indeed, one interpretation.
Here’s another. Russian President Vladimir Putin has predicated his invasion of Ukraine on his premise that Ukrainians are Russian, and all he’s doing is reuniting the people. Given that, the Ukrainian move into Kursk isn’t at all an invasion.
It’s just a bunch of Russians going home.