I agree with Hangershuffel on what we will do, I don't agree with that is what we should do.
I have said on many occasions, this is being very carefully played out to try and not set off particular triggers, and give particular political ways out.
A fuse to the situation could easliy have been done, and still could be. Western forces at the Invitation of the Ukrainian government and on the ground. Russia does not, and will not risk open warfare with powers in particular us, that could give him a blood nose.
He would be as mad as hell, and their would be economic consequences. But the fact its a sovereign country and they can invite who they like in is their business.
This could quickly be cleaned up by Western forces once the Russians are bought into line, hell the Ukrainians have been doing it with one hand and foot tied behind their back.