As I’ve mentioned before the M-138 strip cipher was the State Department’s high level code.
This material (O-1 strip ) was given to the Germans in 1941 and it allowed OKW/Chi and Pers Z to read messages but with a time lag of months.
In early 1943 the Germans and the Finns managed independently to break into the new strips used at the time between European embassies and Washington. The Finns shared this information with the Japanese and offered to cooperate.
However there is no sign that the Germans shared their success with the Japanese at this time.
In summer 1944 the Japanese military attaché in Budapest ,Colonel Tahei Hayashi, reported to Tokyo that the Germans for their own reasons had agreed to share their results on US codes with Japan. In a following message he mentioned the codes given to him.
The Allies learned of this by decoding the relevant messages but with a time lag of roughly four months.
Here are the decodes :
Notice that the strip Washington-Berne was not given even though both Huettenhain ( chief cryptanalyst of OKW/Chi ) and Pers Z personnel mention it in Ticom reports as being read.Could it have something to do with the OSS messages passing through?
Source for the decodes : HW 40/132 ''Decrypts relating to enemy exploitation of US State Department cyphers, with related correspondence''