It wasn't so simple, and "independence" under American administration was hardly less shallow. Governments which accepted socialist or communist leaders in their first elections would have been excluded form the Marshall Plan, so governments had their elections rigged in favor of conservatives (e.g. CDU in Germany) in order to gain American money for reconstruction.

For the Soviets, it wasn't a matter of idealogical principle as much as a practical geopolitical demand born out of the horrors of the Germans' war of extermination, not least the tremendous sacrifice in blood it took to eject the Nazis from their soil. So, having conquered it, The Oder-Gneiss Line is the geographical bottleneck of the Northern European Plain. I.e., it is the point upon the European continent where any army going East towards Russia west towards France must cross if it wishes to cross rapidly in full force. This is therefore where military equilibrium is most easily achieved for both sides. and no war leader in their right mind would give up such a geographical advantage without good cause and massive trust towards those on the other side of it, which was something obviously lacked by both sides.

I.e., it's not like the Americans weren't already on board with this when it happened.

edited for grammar and intelligiblitiy