Peter Robinson asks a good question. In the short run, Soviet control of Poland may have not been impacted by different Western behavior at Yalta. However, several things ought to be kept in mind. Having nearly lost the war to Hitler, and having emerged with a large army, but with the country in ruins, and behind in new weapons technology, Stalin was exceedingly cautious in the immediate post-war period, probing his way. As a result, a strong Western rejection of the legitimacy of the Soviet-installed government in Poland, and its continuation of the endorsement of the London-based Polish government, may have given Stalin pause. Moreover, even if this was not the case as far as Poland was concerned (Stalin obviously believed that Russia had important historic claims on Poland), he may have thought twice about bringing the Polish model to the other countries. Yalta effectively gave Stalin peace of mind, accepting that his legitimate sphere of influence would be defined by the Red Army’s 1945 reach. Moreover, there were several periods of upheaval in Eastern and Central Europe in the years to come, following Stalin’s death in 1953, again in 1956, etc. I happen to believe that the failure to legitimize the initial Soviet domination may have made a pivotal difference during one of these upheavals, bringing down the whole house of cards long before the Velvet Revolutions of 1989.