We were completely disoriented, we had no idea about the Ribbentrop-Molotow pact. We did not know if they [the Soviet army] were coming to join us in our fight against the Germans or if this was a new attack. When we started to fight and the Soviet planes started to drop bombs on us, it became clear what was going on [...]
Polish Army Officer whose unit was stationed on the Polish-Soviet border in September 1939.
PHOTO Left: Soviet and German Tank Crews, PHOTO Middle: Soviet troops on the move towards Grodno, PHOTO right: The Chicago Tribune, September 17, 1939: "Reds Invide Poland: Russians cross border to 'Protect Minorities'"
It became apparent that all that was needed was an initial attack of the German Army and, after that, the attack of the Soviet [Army]; in order to leave nothing of [Poland,] this monstrous bastard of the Treaty of Versailles ... 
Soviet Prime Minister in his speech to the Supreme Soviet on September 31, 1939 about the German-Soviet invasion of Poland.
[The German-Soviet invasion of Poland was] an example of cooperation of socialist nations against Anglo-French imperialism.
An appeal issued by the Communist International on October 7, 1939 - that is, the 22 Anniversary of the October Revolution
When the Soviets fought their way into the city, the fate of the defenders [of Grodno]  and civilians was tragic. Some of them were laid [alive] on the street and then they were crashed by tanks. Several hundred others were shot at the outskirts of the city. There were many school children among them. There was also a “wall of the dead [bodies]” on the city plaza.
Polish national, resident of the besieged Grodno.
The deadly monster trundled forward, and I, crazed, rushed straight towards it. Indescribably grinding … the [Soviet] tank stops right in front of me. Tied to the front [armored] plate of the tank, I see young child, a boy with his arms and legs outstretched. The blood from his wounds is streaming through the metal. Danka and I begin to untie the tied up, outstretched arms and legs of the boy. I am oblivious to everything around me. Then, dressed in black a tank crewman jumps out. He is holding Browning [handgun] in his hand, then another one jumps out – he threatens us … He doesn’t exist for me.
All I can see are the frightened eyes of the child, and his suffering. I can see, how he reaches towards me with his freed fragile arms with boundless faith. With one confident move the tall Danka picks the child from the tank and lie him on the stretcher. I am already by his head. We grab the stretcher and – leaving the dumfounded executioners behind – we run towards the hospital. The boy has five gunshot wounds … and had lost a lot of blood, but he is conscious.
At the hospital he is surrounded by nurses, doctors, and patients – “I want my Mom” – the child says. His name is Tadeusz Jasinski. He is 13-years old. He is the only child of Zofia Jasinska, a maid. He doesn’t have a dad. He was raised by Zaklad Dobroczynnosci, a charity.
He went to fight, threw a bottle with gasoline at the tank, but didn’t light it up, he didn’t know how … They jumped from the tank, beat him, wanted to kill him, and then they tied him up to the front of the tank. Danka brought his mother. The blood transfusion is not helping. The boy, weaker and weaker, begins to slip away. But, he is dying in his Mom’s arms, on this tiny strip of what still is Free Poland. For now, the military hospital is still in our hands”. 
Polish national, in the Soviet-besieged city of Grodno in September 1939
TRANSLATOR'S NOTE: On September 14, 2009, the president of Poland Lech Kaczynski posthumously awarded the young Tadeusz with Commander's Cross of the Order of Merit of the Republic of Poland. See: The Last Speech.
The Nazi ideology, just like any other ideology can be either discarded or assimilated. This is only a question of one's political outlook. But, we all realize, that an ideology as such can not be destroyed by force, and that war is not an appropriate method of annihilating it. For this reason, a war having as its goal destruction of Nazism through power, not only doesn't make any sense, but it is also criminal.
October 31, 1939 speech
Presented by Viktor Suvorov, former Soviet military (GRU) intelligence officer at the United States Naval Academy, October 7, 2009
(PHOTO left: German troops invade Poland from the West) Actually, the "invaders", were German troops in Polish uniforms attacking a German radio station in Gleiwitz (pol. Gliwice). This was certainly convenient for Germany. Without the radio station "attack", the public would have had to WAIT for reporters to get to the scene. And who's to say there wouldn't be non-Nazi reporters in the midst asking troublesome questions?
Poland expected an invasion and had made such preparations as possible for it. This was a plan of holding, falling back, protecting sources of supply, strengthening the line of defense and counter attack. This persisted for more than a week, as German troops puzzlingly failed to penetrate past the Vistula and Bug rivers. Polish troops retreated to this area and south to the "Romanian Bridgehead", from which it could expect supplies from its allies to continue the eastern front against Germany.
(PHOTO left: Russian troops invade Poland from the East) This surprised the western powers which suddenly lost one of the war fronts. This surprised Poland, which also had a treaty with the USSR - the Riga Peace Treaty. The Romanian Bridgehead plan was dead as was any pretext of Polish independence for years to come. Certainly there was no Polish nation until 1945. Not till the elevation of Gomulka following the death of Stalin and Beirut was there a pretext of independence. Not till the fall of the successors of the PPR (Polska Partia Robotnicza - Eng., Polish Workers' Party; Polish Communist: communist party in Poland from 1942 to 1948) a generation later was there truly an independent Poland.
Map source: Wiki
"The Politburo had from the first called the operation a 'liberation campaign', and later Soviet statements and publications never wavered from that line. On 30 November 1939, Stalin stated that it was not Germany who had attacked France and England, but France and England who had attacked Germany; and the following March, Molotov claimed that Germany had tried to make peace and been turned down by 'Anglo-French imperialists'. All subsequent Soviet governments denied that there had ever been a secret protocol to the Molotov-Ribbentrop Pact; but when the document was 'found' in the Soviet archives in 1989, the truth was finally acknowledged. Censorship was also applied in the People's Republic of Poland, to preserve the image of 'Polish-Soviet friendship' promoted by the two communist governments. Official policy allowed only accounts of the 1939 campaign that portrayed it as a reunification of the Belarusian and Ukrainian peoples and a liberation of the Polish people from 'oligarchic capitalism.'" Source: Wiki
PHOTO left: September 23, 1939 - the joint Soviet - German victory parade in the Polish city of Brest. After conclusion of the parade, the Soviet Red Army's Major General Semyon Krivoshein (right) congratulated his German counterpart, General Heinz Guderian (center) on successful completion of the joint invasion of Poland. Krivoshein also offered warm welcome to the Wehrmacht in Moscow, after its forthcoming victory over Great Britain.
German Neo-Nazis have generally targeted Turks, but have found time to attack Polish property. Neo-Nazism is actually stronger in Russia, where it thrives on Russian ethno-phobia. Again Poles have to share enmity with Jews, Asians (Turko-Mongols), and Arabs; and are presently less a target.
PHOTO: Vyacheslav Molotov, the Soviet Prime Minister during his visit to Nazi Germany in November 1940. Read more about Nazi-Soviet Economic Relations here.
1) Whip up and play to fears of NATO.
2) Tap into Ethno-phobia with anti-Polish feeling being it's leading "product", trying to co-market that with the Byelorussian Communist Party and perhaps the Ukrainian Communist Party.
3) Re-validation of the Russian Communist Party as defender of "Mother Russia".
4) Support the Vladimir Putin ensconced hierarchy of Communist era apparatchiks, especially the KGB, and its message that Russia needs a strong man to lead it.
To some extent this gives rise to a new love-hate relationship with neo-Nazis: Promote the "strongman" paradigm of leadership. Promote the same antipathies for non-national ethic groups. Encourage an intolerance for civil liberties.
But they both want that market to grow and will nurture it along. The communists have a large established edge. They are "inside" and have the secret police databases (though it is also likely that one or several neo-Nazi moles have been clever enough to spirit some of this out). Communist era military mores and institutions will be hard to co-opt, no matter how "Nationalistic" an outside group may claim to be. (PHOTO: August 23, 1939 - Vyacheslav Molotov , the Chairman of the Council of People's Commissars of the Soviet Union, signing the Nazi-Soviet Pact. Joseph Stalin and Joachim von Ribbentrop, the Nazi foreign minister, standing behind.)
... especially since there is a large nuclear stockpile that hadn't been launched during even the hottest times in the Cold War. Neo-Nazis advance the Communist agenda without threatening, and in all probability strengthening, Communist power.
One would think that the anti-communist right would have some sympathy for Polish concerns in regard to World War II. However, the fall of the Soviet Union has led neo-isolationists on the right to join others on the quasi-pacifist left, to venture a theory of Polish intransigence as cause for a "needless World War". Both, interestingly enough, are anti-Israeli. Poles and Jews the world over may again have much in common and much to work together on.
It's not that there is no element of truth is some allegations regarding Poland in the interwar period, but that the truth must be weighed among all factors and, in the balance, Poland has the right of it. Here are some claims regarding Polish "provocation".
The Polish people had long been partitioned between Germany (and its Prussian precursor), Russia and the Austria-Hungarian Empire. From the collapse of Russia under the Bolsheviks, and the defeat of Germany and Austria the country of Poland was reconstituted. As would be expected there was and remains a polyglot of non-Polish ethnicities encompassed within these borders. Poland's public policy was that all were equal before the law, but we should be reasonable. It is too likely that some of the old Polish "second class citizens" might feel their oats and be oppressive to some of these, and in particular Germans, and get away with it through the intentional blindness of some of the new government authorities. Much of this would be attributed less to ethnicity that to religion, the Germans usually being Lutherans and the (Slavic-identified) Poles being Catholic.
That said, there isn't much evidence of a centrally orchestrated effort to either drive Germans (or anyone else) out or render them disenfranchised. A goodly number of both Poles and Germans, it should be noted were Jews and it would be poor policy to oppress too significantly those with friends in both camps. Poland, itself, faced with Germany on the west and Russia on the east had no incentive but to encourage harmony and loyalty among all ethnicities. This policy bore fruit during the war and occupation in cooperation and coordination among resistance movements.
There were two simple solutions to the isolation of East Prussia from the rest of Germany: 1) Give East Prussia and it's ethnic Germans to the Poles; 2) Give the Danzig/Gdansk Corridor and its ethnic Poles to the Germans. Neither would be acceptable to both countries - and quite obviously so. Retaining East Prussia should was seen as a tribute to the pride of the modern German State. It was an inconvenient but reasonable concession to a defeated Germany, which lost Alsace-Lorrain to France. The Danzig/Gdansk corridor was vital to Poland's access to the sea, both in traffic on the Vistula and over the rails.
This pretty much eliminates the first proposed "compromise" - a trade of land. It has been ventured that Germany offered to trade the Danzig/Gdansk Corridor for Lithuania, parts of Czechoslovakia, or parts of the Ukraine, a rather generous offer to have other nations bear the burden of German acquisition - to which ascent would hardly be voluntary by such peoples. It's amusing to consider resolving the issue of Kashmir, by say giving Myanmar, perhaps Thailand, and parts of Tibet to India in order to yield Kashmir to Pakistan; or perhaps giving Pakistan parts of Afghanistan, Iran and Tajikistan, while yielding Kashmir to India. Indigenous populations might have other thoughts on the matter.
Another proposal was the creation of a de facto corridor through the corridor, connecting Germany with East Prussia via a rail and highway links removed from Polish surveillance. The natural problem is that the second corridor would block the first. Further, such could readily be used as an invasion route with troop trains simply stopping and disgorging arms and soldiers, easily cutting off resupply of Poland from the Baltic.
Fundamentally, these peace proposals amount to the offer of letting Poland wear a noose, with the promise that of course, no one would ever even think of tightening it. It's all a matter of simple aesthetic taste you see. Poland need only accede and no harm would ever possibly ensue.
Prior to the Molotov-Ribbentrop Pact, Poland was madly pursued with all affection and respect by both Nazi Germany and the USSR. The former offered an Anti-Comintern Pact; while the latter proposed and signed British-France-Russian Anti-Nazi Pact. Both "pacts" called for violating Polish independence; the former by stationing German troops, and the latter by stationing Soviet troops in Poland.
Poland had signed two treaties to try to keep peace with both powers, the 1932 Polsko-Radziecki Pakt o Nieagresji (Eng. Polish-Russian Pact of Nonaggression) and the 1934 Polsko-Niemiecki Pakt o Nieagresji (Eng. Polish-German Pact of Nonaggression). While such a paper peace would be distrusted by all sides, it would at least require formal abrogation prior to hostilities in the expected usages. This would buy time for some mobilization and improved defense.
The single event which expedited World War II in Europe was the Molotov-Ribbentrop Pact. Absent this, the risk was that Poland would exhaust either power effecting an invasion and make it an easy target for the other. With the Pact, Germany could wheel back and smash France (though the speed of this probably shocked Stalin who wouldn't have minded a lingering Western Front). The Soviet Union would have a free hand in the Baltic and the non-aligned Nations in the Balkans. In fact Germany agreed to the Soviet occupation of Bessarabia, which was part of its ally Romania. Both would get a piece of Poland which they had divided since the mid-1700s, until the interruption of the Second Polish Republic.
Illusions that Polish intransigence with respect to German minorities, the Danzig/Gdansk Corridor, and "reasonably appeasing" treaties led to a needless World War II can't withstand any accurate reading of history. Even more, it ignores the experience of nations that slowly yield power to an adversary to prevent hostilities. Further, if we were prepared to set aside the European theater, Germany's alliance with Italy and Japan - both of which were seeking to, and the latter succeeding in, cutting vast swathes of former French and British Imperial domains - would have surely led to the world wide conflagration.