From a Der Spiegel interview with Polish Foreign Minister Radoslaw Sikorski:
SPIEGEL: Why are the Poles so highly engaged in this conflict?
Sikorski: The Ukrainians are our neighbors. They are fighting for the same things we did back in 1989 – for a country that is more democratic, less corrupt and is European.
Read more at Polish Foreign Minister Discusses Weak EU Position in Ukraine Crisis – SPIEGEL ONLINE.