Not sure how you landed in left field on this topic. But you're way off base.
Russia sent unmarked troops wearing uniforms on to Ukrainian territory. Uniformed troops have now surrounded Ukrainian military installations and are making threats. If that isn't an invasion, I am not sure what is.
The Ukrainians had enough of their president, who was going against the vote of a referendum specifically to arrange closer ties with the EU. He was knuckling under to Putin, who wanted closer ties, against the will of the Ukrainian people. And the president was no democrat either, jailing his predecessor on a trumped up charge.
I hate to tell you this but you've been fed a pant load on a steaming hot plate.
This President was duly elected and yes there were monitors in place that actually were amazed how well this election went in 2010.
Don't hand me this shit that this was a move by "all of Ukraine". This coup was led by a small minority in western Ukraine.
This referendum you speak of? Never happened. How's that for you? What had been agreed to in mid February with the EU helping this was a new set of elections to let the people decide.
Oh and btw, the Russians had really offered a sweet deal to the Ukraine a far better one economically than the EU.
No one was knuckling under to anything.
Now on to the Crimea. Putin invaded nothing. Under a treaty from 1997 Russia has been allowed to keep up to 25,000 troops at their naval base. Currently there are 16,000.
This treaty was extended to 2042.
This port in Crimea is home to Russia's Black Sea Fleet. This is no different than your bases in Okinawa or Qatar.
And Russia has a right to protect them.