After established Demilitarized Zone at Belarus, having eastern flank more or less secured, Poles could take another look at western border...or at least line between two armies there. As time goes by, it became clear enough that "German case" cannot be solved step by step. What's more - those "steps" were limited by London and Paris. In fact nor Great Britain, nor France wants to see Germans down on their knees, with Poland as the new European power on their place.   
