"Documents released Monday and seen in advance by The Associated Press lend weight to the belief that suppression within the highest levels of the U.S. government helped cover up Soviet guilt in the killing of some 22,000 Polish officers and other prisoners in the Katyn forest and other locations in 1940.
The evidence is among about 1,000 pages of newly declassified documents that the United States National Archives is releasing Monday and putting online. Historians who saw the material days before the official release describe it as important and shared some highlights with the AP. The most dramatic revelation so far is the evidence of the secret codes sent by the two American POWs — something historians were unaware of and which adds to evidence that the Roosevelt administration knew of the Soviet atrocity relatively early on.
The declassified documents also show the United States maintaining that it couldn't conclusively determine guilt until a Russian admission in 1990 — a statement that looks improbable given the huge body of evidence of Soviet guilt that had already emerged decades earlier. Historians say the new material helps to flesh out the story of what the U.S. knew and when."