In the run-up to World War II, the Brits, in their wisdom, guaranteed the Poles that they'd defend the Polish border from Hitler for them, which Britain didn't have the power to do. This had the effect (Pat wrote) of making the Polish government idiotically self-confident and cocky. So much so, that they refused to even discuss the German territory that had short-sightedly been awarded to Poland at Versailles. And that territory was old German territory, that had been Prussian territory before the German state even existed. The thought that Hitler, or any German leader, would let that state of affairs continue indefinitely was just plain stupid.
My own thinking is that if the Brits had kept their busybody noses out of it, the Poles might very well have been sensible and prudent enough to negotiate with Germany, and have ceded all or part of the disputed territory to Germany, and conceivably even have ended up with an alliance with Hitler to protect them from the Soviets, and the war just might have been avoided entirely.
Now we have a similar situation. When the Soviet Union fell apart, things were so disorganized that Ukraine, traditionally a part of Russia anyway, became an independent country with enormous numbers of Russians in it, most significantly in Crimea.
Now we have nutcases like McCain, and draft-dodger Joe Biden, running around squawking that we'll defend any number of places from Putin. The deep-thinking neocon philosophers, also mostly draft-dodgers, are ramping up the war talk as well. Could this make the governments of these countries as adamant and pig-headed as the Poles were decades ago? Human nature being what it is, that's quite likely.