I always thought it was FDR, not Eisenhower who sent the Russian soldiers to their deaths. I don't remember any book or professor saying that the president fully knew what was going to happen. Possibly he was too worn out to dwell on it. FDR was half dead for most of his fouth term.
I think Eisenhower was a general in Europe at the time and it was Roosevelts deal with "Uncle Joe" Stalin.
I also think FDR agreed to honor the Molotov / Ribbentrop agreement.