The answer, in summary: He was told pretty much everything, but refused to believe much of it.
From page 15:
On May 17, 1939, Proskurov [Stalin’s Warsaw Intelligence Chief] sent a report to Stalin with a six page attachment entitled “The Future Plans of Aggression by Fascist Germany in the estimation of an Official of the German Foreign Ministry, Kleist.”
The report was classified “Top Secret” and “Of Special Interest.” Provided by the Warsaw residency of Soviet military intelligence, it was based on a briefing given by Dr. Peter Kleist, head of the eastern Department of Ribbentorp’s office, to senior officers of the German embassy in Warsaw during Kleist’s visit there on may 2, 1939.
Coincidentally, May 2 was the day Stalin informed Maksim M. Litvinov that he would be replaced by Molotov as commissar of foreign affairs. Litvinov was Jewish and had favored an agreement with England and France to curb Nazi aggression. Thus, Stalin’s action was a signal to Hitler of the possibility of an agreement between their two countries. This was to be one of the first steps in a minuet that would be danced by Moscow, Berlin, London, and Paris during the next few months over the question of what to do about Poland.
Kleist’s comments on Hitler’s plans for Poland and his longer-range intentions must have been read by Stalin with great interest. Kleist, after all, was the one person in Ribbentorp’s immediate entourage who was continuously involved in German actions in Eastern Europe. He began by stating that,
“Germany at the present moment is in the first phase of its military consolidation in the east, which, without regard to ideological considerations, must be achieved by whatever means. After the merciless cleansing of the east will come the western phase that must end in the defeat of France and England either by military or by political means.
“Only after this can one count on the feasibility of the destruction of the Soviet Union. At the present time we are still in the phase of military consolidation in the East. It is Poland’s turn next… The preparations already taken by Germany – the creation of the protectorate in Bohemia and Moravia, the creation of a Slovakian state, the annexation of the Memel region – were all directed against Poland…”
Kleist went on to say:
“Hitler has decided it is necessary to bring Poland to her knees. To a small circle of persons around Hitler, it was known that the last German proposal would be rejected by Poland. Hitler and Ribbentrop were convinced that because of foreign and domestic policy considerations, the Polish government would not accept the German demands. Only for this reason could Germany have been able to insert the point in its proposal on guarantees of the inviolability of frontiers for 25 years. German calculations were correct. On the strength of Poland’s refusal, we now have a free hand in dealing with her….”
Kleist’s next words were harsher:
“If Poland does not agree to German proposals and does not capitulate in the weeks ahead, one can scarcely doubt that in July, August she will be the victim of a military attack… Major strategic opposition by the Polish army will be overcome in 8 – 14 days. The attack on Poland will be carried out simultaneously from Germany’s eastern borders, from Slovakia, Carpatho-Ukraine, and East Prussia. The offensive must be carried out in the fiercest way and, as the German general staff conceives it, should lead to a stunning success. The remaining centers of opposition will, without doubt, exist in the entire country will be suppressed in the most merciless fashion… German preparations against Poland have been postponed to July-August. Military measures will be undertaken not long before the offensive. They must be executed thoroughly and completely camouflaged.”
Kleist concentrated on the themes for a propaganda offensive against Poland, listing the ploys and slogans that were to be emphasized in the campaign:
“Under the slogan ‘Poland – State of Reaction and Decay,’ we must reveal the poverty of the Polish peasants, the cultural backwardness of the country, the feudal methods of running the economy and existence of a starving Polish population… The goal of this campaign is to effect world public opinion and the Polish population; one must achieve a split within the Polish nation and dissatisfaction with the Polish leadership on the part of the Polish population, exploiting class differences. Preparations for the propaganda attack against Poland will take about two months."
Kleist examined various situations that would provide Germany with a pretext for initiating military actions:… Kleist’s view of the future was oddly prophetic:
“We adhere to the view that a conflict with Poland can be localized. England and France, as in the past, are not ready to act on Poland’s behalf. If we crush Poland’s main opposition in a short time, then England may demonstrate with her fleet in the Mediterranean. France will rattle its guns behind the Maginot line – that will end the affair.
“If, despite expectations, a European war begins in connection with a German attack on Poland, then we’ll know that a German strike against Poland will serve as a pretext for a preventative war against Germany by the Western powers – something agreed on in advance… If this happens, Hitler will be ready to engage in lengthy discussions. In any case, we will not allow ourselves to be provoked at a time not of our choosing. Choice of the moment for action we reserve to ourselves. At present we have decided not to involve ourselves in a European war as a result of our inadequate readiness and, for us, the unrewarding international situation; however in three or four months we can be completely ready.
“The German command is convinced it will be victorious… because of our aviation. According to the calculations of our military specialists, all the ports of England can be destroyed within six hours. The destructive action of German aviation has up until now, been demonstrated only once, during the Spanish civil war in the port of Guernica. The success was stupendous – the city was flattened. In this light, the defeat of England and France will not be a difficult affair… America will not intervene in time and the Soviet Union will stay neutral.”