Japanese warships stopping and searching Russian merchant ship according to the U.S. Joint Intelligence Committee. Daily summary dated 26 March 1942

An item reported that according to Soviet sources Japanese warships stopped and searched all Russian ships. Since mid-January Soviet merchant ships bound for the USA or Petropavlovk, Kamchatka now took the route via the Straits of Tsushima. The passages via the Straits of Tsuburu and La Perouse were denied and believed to be mined.

Source

Map Room Papers (Roosevelt Administration), 1942 - 1945. U.S. Joint Intelligence Committee. Daily summary No. 106 dated 26 March 1942