You got a point, they were cowards and let down an ally. But at least they were not partners in crime as USSR.
Is that why polish officers asked their Red Army captors to increase the number of their guards, when passing through Ukrainian villages in Western Ukraine?
It's a bit odd you seem concerned with Czecoslovakia's destiny at the hands of Germany as USSR occupied them much longer afterwards.
Seeing, how Czechs diligently produced weapons for Germany throughout the entire war - I have little sympathy.
Germany was certainly waiting for an opportunity to attack Poland, Stalin chose to sell them an insurance policy in exchange for half Poland, the Baltic States and Finland (three wars of agression). The people of USSR would later pay dearly this gamble made by Stalin. Sadly, they didn't made him pay for this huge mistake and many still praise him. I think Russia is a great people because they won despite him.
I know of Soviet invasion of Poland (over which the West did NOT declare war - interesting, isn't it?), of Soviet Winter war with Finland, but can you tell me the battles that occurred during the war between USSR and Baltic states? Or the dates? I was under the impression, that those 3 countries held a plebiscite to become a part of USSR, and no fighting was involved.
But seriously, had Stalin not say yes to M-R, USSR would have been in a much worse position in 1941. Hell - half of Poland that went to USSR was what the UK and France said should go to Moscow back in 1920! Poland conquered it from a country torn by civil war. So you can say, that Stalin just took it back from the thief!