Ukraine
I don't really follow foreign policy as much as I could. I mean, I think I know more about the larger world than most people and a fair amount about economics and the military, but I know that I don't really understand international diplomacy. Thankfully there are people I know who are much better at this than I am. When looking at the Ukraine situation, amateur that I am, my inclination was to view the matter exclusively as a contest involving the leaderships of the Ukraine, Russia, and the US. But there are other countries nearby that might have both opinions and capabilities to express those opinions, and as Erik Fogg points out that NATO's eastern members are very interested in the matter and have their own capabilities to intervene and potentially drag the rest of NATO in. Which presumably plays into the calculations being made in Kiev and Moscow and Washington.