This seems to lead to US National Archives collection RG 84 ‘Records of Foreign Service Posts of the Department of State’.
The NND number doesn’t seem to be 857570 because that code is associated with reports of the ‘Supreme Headquarters Allied Expeditionary Force. Office of the U.S. Political Officer. 2/13/1944-ca. 9/2/1944’.
Other combinations such as 851510, 857510, 851570 are not valid.
This leaves NND 857560. This code tracks to RG 84 ‘Sweden’ - Entry 3198 ‘Top Secret General Records, 1944 – 1952’.
This makes sense as that report was sent from the US embassy in Sweden.
Box 1 of entry 3198 says ‘Telegrams Sent and Received Relating to Finland, 1943-1945’.
One would expect to find the Carlson-Goldsberry report there.
So when I told my researcher to check this box I expected that I would be able to get the reports sent from Sweden in late 1944 summarizing the talks US officials had with the Finnish codebreakers.
Unfortunately both my researcher and the NARA FOIA office have confirmed that these reports are not there!
So why does the note say RG 84 box 1 NND 857560?
I’ve asked the NSA FOIA office if they can give me more information on where they got this document. If they respond maybe I will be able to track down similar reports in NARA.