Having studied the Soviet Union excessively, Katyn was a number of things:
1. It was Stalin's war and dominance of Poland in the agreement that with Hitler it would be invaded, and with such any country invaded by the Soviet Union would suffer mass casualties by what was determined by Stalin's social engineers and tactic officials. In Ukraine the massive peasant class was to be reduced (which it was) by several million; and so the NKVD organized mass starvations and executions. Essentially as read in the documentation below, part of the plan was to weaken intelligentsia within Poland (meaning high ranking official associated with government) making it easier for the Soviet government to take power and maintain it. There were also constant prosecutions of such intelligentsia throughout Soviet control of Poland which included high ranking clergy, government officials, industrialists, military generals, academics.
2. The second was that all this occurred during the Great Purges or also known as the Great Terror. Surrounding these years many were executed, or detained to Gulags to die. Reason being that there wasn't much reason, other that Stalin's egotistic 'cult of personality' and the constant low minded fear and mistrust in the Public. The NKVD massively led these purges and went by numbers and quotas rather than names and justice. Each city and district within the Soviet Union and states under its control were administered with quotas from the Kremlin, which eventually was put upon to society. NKVD officers would just arrest at random; the matter which had the most effort was when they went to civilian communities anywhere, took the head of the community and ordered him/her to put 5 to sometimes 20 names on a list. If they failed to do so by the next morning here the NKVD would come to collect the list, that person and their families would become all the blank spaces on the list for failing to follow orders. Then the next night in the deep hours of midnight, they would be arrested and never seen again. Millions died of these purges. Some massive targets were religious icons, anti-Soviet ailments, and immigrants. Immigrants were a special case, anyone with partial or full ethnicity other than Russia going back at least a generation was ordered into exile; if protested they were shot. However Poles were and exception that were living in Russia, most were shot (about 25,000 to 50,000 estimated) without warning. The remaining 40,000 or so fleeted back to Poland. Ironically only to be invaded by the Soviet regime again.
3. It was under treaty with the Nazi Germany. The Katyn forest massacre was in away planned out in many of the documents immersed during the two year allied ship between Stalin and Hitler. Yes, Poland was to be invaded, and yes quotas were made in the thousands to target high ranking officials and again intelligentsia. Of course it wasn't listed or planned out as the Katyn forest massacre, but those individuals were most likely going to die without doubt.
4. This fourth point isn't in fact but rather many assumptions made by historians. Stalinist Russia was a place with systems and functioning woven so deep that not even highest ranking officials of the Kremlin knew of them. It is known that Stalin had tons of academics working for him. Sociologists, biologists, political theorists, chemists, economists, geneticists, psychologists, etc. The majority with doctorates, some from even American universities. At the collapse of Stalin, and even at the end of the Soviet Union many of the documents, journals, and projects all these academics worked on were stored in mass archives in the bunkers/basements of the Kremlin and Lubyanka; many were also burned and shredded. However the few that did emerge contained disturbing revelations. All the way from eugenic prophecies to human mind control to population exterminations to chemical and biological warfare technologies to social engineering at the darkest of levels. Tons of scientific theories many attempted to be proven by highly unethical and immoral experimentation whether it be on innocent individuals or populations of individuals. (ie. They would take apart someones brain piece by piece (while alive) to determine certain psychological phenomena, test bio-warfare diseases on innocent individuals, etc. etc.) So it might not be surprising if the Katyn forest massacre was an underground project of Stalin to promote such social engineering supported by ill- minded theories on eugenics and or social darwinistic theories.
Here is an interesting fact, all the 20-35 NKVD officers whom were responsible for the executions of the Katyn Poles (whom wore leather butcher dresses to prevent the blood and brains from seeping onto their uniforms) were each awarded the Order of Lenin for brave and heroic actions toward the Soviet Union. In a couple of years, over half of them would perish in Stalin's second Great Purge, and the rest would die of natural age before the collapse of the Soviet Union. The hypocrisy and irony of it all.
Below I have attached a document signed by Stalin and Beria (Stalin's second hand man). Basically it says in Russian the patriotic reasons and permissions to go on with the executions. *Please click the image for a readable higher resolution.
More images:
American and British POWS were brought by Nazi's to ridicule the barbarianism of the Soviets, when ironically it was the Nazi's that collected those 25,000 Poles and handed them over to the Russians with pride.
Again more propaganda and hypocrisy on the Nazi side to depict the barbaric acts of the Soviet regime.
The Poles being marched to Katyn. NOTICE the Red Army soldiers in front, and the German soldiers to the side of the marching line; look closely to see their distinguisable helments.
The massacre:
Modern rememberance:
Never forget what tyrants did to our innocent people!