400 men. Guard forces or Keibitai: detachments of 200–500 men who provide security to Imperial Japanese Navy facilities Pioneers or Setsueitai built naval facilities, including airstrips, on remote islands. Naval Civil Engineering and Construction Units, or Kaigun Kenchiku Shisetsu Butai The Naval Communications Units or Tsushintai of 600–1,000 men to provide basic naval communications and also handled encryption and decryption. The Tokkeitai Navy military police units were part of the naval intelligence armed branch, with military police regular functions in naval installations and occupied territories; they also worked with the Imperial Japanese Army's Kempeitai military police, the Keishicho civil police and Tokko secret units in security and intelligence services. Personnel strength December 1941 — 291,359 including 1,500 pilots July 1945 — 1,663,223 See also Imperial Japanese Navy in World War I Imperial Japanese Navy order of battle 1941 List of Japanese Navy ships and war vessels in World War II List of ships of the Second World War Naval history of World War II Osaka Guard District Notes References Bibliography World War II World War II naval ships of Japan Naval history of World War II