The top part from the August 1 memo doesn't appear to be kerned. The bottom part from the August 18 memo does appear to be kerned. Perhaps it is due to artifacts from the copy process. I think the MS Word document that matches it exactly was made with kerning turned off (the default)
I've seen arguments both ways about MS Word, but your evidence is very interesting.
My eyes are getting tired, glad I don't do this for a living anymore.
I saved the picture posted and double-clicked the file name which was saved. This caused the saved picture to be brought up in the MS picture viewer. I then placed the cursor over the "fe" in the word "interference". Right-clicking allows selection of "zoom in" and repeated clicking will zoom in very closely. It would be my assessment that kerning is visible in this letter combination. It appears that the "e" is partially under the top of the "f".
Perhaps somebody more expert in typography and kerning would comment on this specific detail and/or capture and post the enlarged image.