Soviet escort vessels or S-class destroyers of the Baltic Fleet sighted in July 1936 according to report No. 9697 dated 8 February 1937

Three escort vessels of destroyers S-class operated in July. Further more was an escort vessel of a distinctly new type sighted while executing trial trips. The displacement was estimated to be 500 tons and the length 55-66 metres. She was armed with 1-10.2cm gun on the foredeck and 2-4.7cm anti aircraft guns mounted on the quarter deck. Her engines were extremely noisy especially at the full speed 18 knots. Furthermore fitted out with minelaying gear.

Source

National Archive. Record Group 165: Records of the War Department General and Special Staffs Series: Security Classified Correspondence and Reports. File Unit. Russia: Navy - MID 2503-16 THRU 2503-265. Roll 1443.