Imagine, if you will, Hitler stopping at Poland and the Allies negotiating a peace treaty that lets him keep it. Move the clock 30 years forward. On all maps, Poland is now Germany. Nobody's too ecstatic about it, but a great portion of the world no longer views Poland as Poland. Many Poles (most of the young, possibly even a majority of the nation) self identify as Germans.
A small, dedicated resistance has been active all of this time, waiting for their chance to retake their country. These freedom fighters reach out to the rest of the world and ask for our help. What do you say? Do you say, "well, it's been 30 years, you know, a lot of your people are perfectly fine being Germans, why are you causing such a fuss?" A nation has been annexed, and, for all intents and purposes, it's looking a heck of a lot that the annexation will stick. It also seems apparent that these freedom fighters are vastly outnumbered and don't stand a chance. What do you do?
Do you let Poland naturally morph into what many Poles now perceive it to be, based on what it's turned into? Or does the historical identity of Poland, the Poland of 30 years ago, the 'unadulterated' representation of Poland, have a right to be restored?