"The interests of the communist parties of these countries were obviously not the same as the interests of the countries" 
 That's a subjective and personal opinion.Who decides if the they had interest of their countries in mind or not ? They were perfectly legally reckognized socialist states led by socialist parties, like or not. Per international law they were governing this countries. 
 In any case you didn't read the source in detail as it clearly writes about unreckognized borders and that fear of re-militarized Germany was major motivation.