Presence of legitimate interests on the territory of another nation does not create an excuse for insertion of troops in this manner. Purely peacemaking force insertion might be justified in case of a humanitarian crisis, but not such crisis exists. Typically, the UN or some other international body authorizes a peacekeeping operation.
Absence of national insignia, by the way, is also contrary to all norms of war; these "green men" cannot be afforded the protection of the Geneva convention. They are already war criminals simply for not identifying themselves.
I think Putin is only interested in keeping the commerce moving. The UN...hah. The Geneva Convention...ptooie. The whole thing is a joke.
You mean like when the US invaded Iraq?