Soviet Union wanted to built battleships with a maximum caliber of 40.6cm/16” guns according to a memorandum of US secretary of the Swanson dated 10 April 1937

In a memorandum for president Roosevelt wrote secretary of the Navy Swanson (1) on 10 April 1937 regarding the caliber of the main guns for new battleships that the Soviet Union preserved for itself the right to build prior to 1 January 1943 battleships to be armed with a maximum caliber of 16”. The proposal of the United Kingdom to arm the first two battleships with 38c,/15” instead of 40.6cm/16” guns was refused.  

Note

1. Claude Augustus Swanson (31-3-1862 Swansonville, Virginia, USA-7 July 1939 Rapidan Camp, Virginia, USA) secretary of the Navy 5 March 1933-7 July 1939.

Source

Franklin Roosevelt D. Roosevelt Presidential Libray&Museum. Map Navy Department October 1936-1937 FDR’s President’s Secretary’s File (psfc000057).