Japanese Monograph No. 106

NAVAL OPERATIONS AGAINST SOVIET RUSSIA

PREPARED BY

MILITARY HISTORY SECTION

HEADQUARTERS, ARMY FORCES FAR EAST

DISTRIBUTED BY

OFFICE OF THE CHIEF OF MILITARY HISTORY

DEPARTMENT OF THE ARMY

This monograph was compiled by Comdr Shiro Yamaguchi, former staff officer (Operations), Imperial General Headquarters and Comdr Tadao Kuzumi, former staff officer (Intelligence), Imperial General Headquarters. This record was compiled from various battle reports of units involved in the operations, the personal papers and recollections of the compilators and interrogations of Japanese officers concerned with the operations.

Additional monographs covering the operations of the Japanese Armed Forces against Soviet Russia are as follows:

Title

Period

Mono No

Operations Record Against Soviet Russia, Vol. I

Jan 43 - Jul 45

138

Operations Record Against Soviet Russia, Vol. II, Part I

Jul 45 - Sep 45

154

Operations Record Against Soviet Russia, Vol. II, Part II

Jun 45 - Sep 45

155

Air Operations Record Against Soviet Russia.

Jun 41 - Sep 45

151

24 January 1952

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Preface

Through Instructions No. 126 to the Japanese Government, 12 October 1945, subject: Institution for War Records Investigation, steps were initiated to exploit military historical records and official reports of the Japanese War Ministry and Japanese General Staff. Upon dissolution of the War Ministry and the Japanese General Staff, and the transfer of their former functions to the Demobilisation Bureau, research and compilation continued and developed into a series of historical monographs.

The paucity of original orders, plans and unit Journals, which are normally essential in the preparations of this type of record, most of which were lost or destroyed during field operations or bombing raids rendered the task of compilation most difficult; particularly distressing has been the complete lack of official strength reports, normal in AG or G3 records. However, while many of the important orders, plans and estimates have been reconstructed from memory and therefore are not textually identical with the originals, they are believed to be generally accurate and reliable.

Under the supervision of the Demobilisation Bureau, the basic material contained in this monograph was compiled and written in Japanese by former officers, on duty in command and staff units within major units during the period of operations. Translation was effected through the facilities of Allied Translators and Interpreters Service, 02, General Headquarters, Far East Command.

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This Japanese Operational Monograph was rewritten in English by the Japanese Research Division, Military History Section, General Headquarters, Far East Command and is based on the translation of the Japanese original. Editorial corrections were limited to those necessary for coherence and accuracy.

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TABLE OF CONTENTS

Chapter

Page

I

Plans and Preparations for Operations

1

Policy During Various Phases of Operations

3

II

Operations Against the Soviet Union

13

Soviet Declaration of War

13

Countermeasures

14

APPENDICES

I

Operational Policy in the Event of War with the Soviet Union During the First Phase Operations

19

II

Naval Operational Policy to be Followed by the Combined Fleet in the Event of War with the Soviet Union During the Third Phase Operations

21

III

Operational Policy for Urgent Havel Operations in the Event of War with the Soviet Union in the Course of Operations Against the United States, Great Britain and China

23

CHART

No 1

Normal Navy Force in Peacetime Organisation

5

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CHAPTER I

Plans and Preparations for Operations

In preparing the basic policy for operations in the event of war with the Soviet Union, Japan's military leaders believed that, in view of the huge Russian Army and the relatively small Russian Navy, any major engagements would be fought on the Asian land mass and there would be little possibility of fighting a heavy naval engagement. Therefore, in the event of war with the Soviet Union, the main role was to be assumed by the Army, while the Navy was to be assigned a secondary role.

The mission of the Navy in operations against the Soviet Union was to conduct extensive antisubmarine operations, effect the speedy destruction of enemy vessels in the Orient and the destruction of enemy air strength in the Maritime Province (Coastal area of Siberia) and the Ussuri area. In addition, the Navy was to support the Army in the invasion of strategic points in the Soviet Par East and provide escorts for convoys and other shipping.

To carry out its assigned role, the Navy planned to gain aerial supremacy in the Japan and Okhotsk Seas by deploying land-based aircraft in North Korea and on Hokkaido. Concurrently the naval base at Vladivostok was to be blockaded by antisubmarine and other light vessels to prevent enemy submarines from operating along Japan's Pacific coast and, in addition, the Straits of Korea, Tsugaru, and Soya were to be under strict antisubmarine patrol. As

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the Navy did not expect full-scale naval operations, it was estimated that the burden of destruction of enemy surface vessels would fall to the air units.

In view of the relatively short distance to the heart of the Japanese Empire from Soviet Far East bases and the unreliable national policy of the Soviet Union, every precaution was taken to avoid a surprise attack by Soviet forces. An intelligence center was established at Harbin and a lookout post was established on the northeastern tip of Korea to observe the movements of the Soviet Fleet in the Vladivostok area. Through these stations and through radio intelligence, the Japanese Navy received general information concerning the activities of Soviet forces.

Although this basic policy was tentatively adopted and detailed plans for its operation were prepared, they were not announced as every effort was being made at this time to prevent friction with the Soviet Union for fear that they would take advantage of some incident to abrogate the Japanese-Soviet Non-aggression Pact. Furthermore, should relations with the United States and Great Britain become strained, it was deemed absolutely necessary to prevent the outbreak of war with the Soviet Union. After the outbreak of war with the United States and Great Britain, it became more and more difficult to engage in naval operations against the Soviet Union, for virtually all of Japan's naval strength was committed against

the Allies.

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Policy During Various Phases of Operations

The policy in the event of war with the Soviet Union during the First Phase Operations (Dec 41 - Apr 42) against the United States and Great Britain was based on the belief that as long as these operations continued there would be no alternative but to assume defensive operations against the Soviet Union. With the outbreak of war between the Soviet Union and Germany and the need to insure the defense of the Japan Sea and the northern area, the Fifth Fleet was activated on 25 July 1941. The Fifth Fleet, under the command of Vice Admiral Hosogaya, was composed of the light cruisers Tama and Kiso, the converted seaplane tender Kimikawa Maru and two torpedo boats. Its mission was to insure the security of surface traffic and provide air defense of strategic points in the northern area. The Fifth Fleet was to complete its preparations for operations in the event of war with the Soviet Union by 20 August 1941 and then patrol the northern area. In the event of operations, the plan called for reinforcing the Fifth Fleet with elements of the inner combat forces, consisting of light vessels deployed in the defense of the Homeland. The basic disposition for these forces in the event of operations against the Soviet Union called for the Ominato Guard District Force, Chinhae (Korea) Guard District Force and the Maizuru Naval District Force, to be committed in the northern area, Korea area and the Homeland on the Japan Sea side, respectively. These forces were strictly defensive

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in nature and their strength at the outbreak of war was small (Chart No 1). The Japanese Navy War Plan had further provided that carrier aircraft of the First Air Fleet and land-based aircraft of the Eleventh Air Fleet would be deployed, if necessary, to north Korea and Hokkaido respectively to reinforce the air strength of the Fifth Fleet. It was also planned that the seaplanes of the surface fleet would be used to support Army units in northern Manchuria in the. event of combined Army and Navy operation along the Amur River.

In addition, air and surface forces were to be assigned to the Fifth Fleet as soon as the state of the Southern Operations would permit. The plan called for no offensive operations against the Soviet Union until such time as the First Phase Operations were successfully completed. If, however, war with the Soviet Union broke out after the completion of the First Phase Operations, it was planned that positive countermeasures would be taken immediately, utilising forces committed to the Southern Operations.

However, with the outbreak of war with the United States and Great Britain, it became necessary to employ the entire strength of the First Air Fleet in the Pearl Harbor Operation and Eleventh Air Fleet in the Southern Operations. It was therefore difficult to estimate the air and naval strength which could have been employed against the Soviet Union had war broken out in the course of First Phase Operations against the Allies.

In preparation for the First Phase Operations, Imperial General

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Station

Normal Navy Force in Peacetime Organization

Converted Ships and Specially Established Force

Ominato Guard District

Ominato Guard District Headquarters

Ominato Naval Harbor Master's Office

Ominato Navy Communications Unit

Wakkanai Navy Communications Unit

Shinko Maru

Ominato Naval Air Group (16 fighters - 8 seaplanes)

Zuiko Maru

Ishigaki, Kunajiri, Hachijo (Patrol Craft)

Chitose Maru

1st Destroyer Division and Okikaze (Destroyer)

27th Minesweeper Division

Ominato Defense Unit

Odomari (Icebreaker)

Maizuru Naval District

Maizuru Naval District Headquarters

Maizuru Naval Barracks

Maizuru Naval Harbor Master's Office

Maizuru Navy Communications Unit

Santo Maru

Maizuru Naval Air Group (6 seaplanes)

35th Minesweeper Division

Maizuru Naval Guard Unit

Maizuru Defense Unit

Chinhae Guard District

Chinhae Guard District Headquarters

Chinhae Naval Harbor Master's Office

Ryotoku Maru

Chinhae Communications Unit

48th Minesweeper Division

Chinhae Air Group (8 seaplanes)

49th Minesweeper Division

32d Destroyer Division, Minekaze (Destroyer)

Seikyo Maru

Chinhae Defense Unit

Shiraume Maru

Rashin Defense Unit

Rashin Communications Unit

Chart No. 1

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Headquarters Navy Section issued Directive No 1 on 5 November 1941 (see Appendix I). Outlined in an annex to this directive was the policy for operations in the event of war with the Soviet Union during the First Phase Operations. This policy was essentially the same as the basic policy except that it stressed the fact that the operations against the United States and Great Britain were to have priority and the only operations to be conducted against the Soviet Union were those required for defense and operations that would not interfere with the Southern Operations.

In April 1942, Imperial General Headquarters Navy Section issued a directive regarding the policy for operations during the Second Phase (Apr 42 - Mid 43). The policy for operations against the Soviet Union in the event of war was identical to the policy for the First Phase Operations. At this time the operation against the Allies was progressing according to schedule. However, it was essential that war with the Soviet Union be avoided, at least until such time as the operation against the United States had been completed. Although every precaution was taken to avoid friction with the Soviet Union, it was thought unnecessary to attach much importance to the possibility of an attack by the Soviet Union as long as the war with the United States and Great Britain was progressing favorably and so long as the Soviet Union was engaged in the Russo-German war.

The preparation of a policy for operations against the Soviet

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Union daring the Third Phase Operations (Mid 43 - Fall 44) was an extremely delicate and intricate problem, for Japan was now on the defensive in its operations against the Allies, and the Red Army had contained the German attack. However, it was believed that as long as Japan retained its fighting potential and as long as the Japanese-Soviet Non-aggression Pact remained in effect, the Soviet Union would not declare war on Japan. Japan did not want war with the Soviet Union and was prepared to go to almost any lengths to prevent it. The policy for operations against the Soviet Union during the Third Phase differed from the policy during the first two phases in only one respect that the policy now placed emphasis on the disruption of communications between the Soviet Union and the United States. The use of bases in the Maritime Province by the United States and the northern contact between the United States and the Soviet Union constituted the greatest menace to Japan. Therefore, it was planned that Okha and Petropavlovsk were to be the initial objectives in the occupation of strategic points and that subsequently Vladivostok would become an objective. The details regarding the policy to be followed by the Combined Fleet for operations against the Soviet Union during the Third Phase Operations were covered in an annex to Imperial General Headquarters Navy Section Directive No 209, March 1943 (see Appendix II).

In early 1945, the war with the Allies was becoming more and

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more unfavorable to Japan. Iwo Jima and Okinawa had been lost and the Allied operations against the Homeland were being intensified. In addition, the Soviet Union had, since August 1944, moved large numbers of troops to eastern Siberia and on 5 April 1945 had announced that the Japanese-Soviet Non-aggression Pact would not be renewed.

The policy for naval operations in the event of Soviet intervention during the final phase of the war was issued on 23 May 1945, in Imperial General Headquarters Navy Order No 41 (see Appendix III). As in the past, it was assumed that the Army would play the main role in the event of operations, while the Navy would defend the waters around the Homeland. Because of the successive transfer of troops to other fronts, the fighting strength of the Kwantung Army had been considerably reduced. Therefore, it was planned, in the event of war with the Soviet Union, that the Kwantung Army would withdraw to the north Korean frontier where it would prepare to resist the Soviet attack. It was also planned that the Kwantung Army would receive some reinforcements by transferring units from China.

Despite the fact that the Navy had already expended its main fighting strength in operations against the Allies, the policy for naval operations in the event of war with the Soviet Union called for support of Army operations, protection of the Homeland (including Korea), securing of strategic positions in Manchuria, Hokkaido,

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Kuriles and southern Sakhalin, control of the Straits of Korea, Tsugaru and Soya, and efforts to disrupt communications between the Soviet Union and the United States. Furthermore, these missions were to be carried out without interfering with the operations against the United States and the preparation of plans for the "Ketsu-Go" Operations.

On 25 April 1945, the Navy General Command was established to unify under one command all naval units in the inner and outer combat zones and, in preparation for the expected Allied invasion of the Homeland, the entire naval strength was readied for the decisive battle. This operation had priority over all other plans and, although plans were made for counter-measures to be taken in the event of Soviet intervention, no concrete preparations were made. Japan's small remaining naval force, greatly reduced in air strength, was committed to operations against the Allies, and the only forces available for use against the Soviet Union were the small defense forces of the Maizuru Naval District, Ominato and Chinhae Guard Districts, and the garrison forces, at minimum strength, of the Kuriles, Hokkaido and north Korea. Also available, under the command of the Combined Fleet, were the small air units stationed in each of these areas. The naval strength of these forces was as follows:

Maizuru area

51st Squadron (2 submarines, 13 patrol craft)

105th Squadron (1 destroyer, 6 patrol craft)

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3 midget submarines

Garrison troops

28 seaplanes, 50 medium and 50 dive bombers

Kuriles

3d Motor Torpedo Boat Division (3 motor torpedo boats)

Garrison troops

4 torpedo bombers

Sakhalin and Hokkaido

104th Squadron (6 patrol craft)

Garrison troops

North Korea

No surface vessels

Garrison troops

Ominato area

28th and 52d Minesweeper Divisions (3 minesweepers each)

52d Gunboat Division (3 gunboats)

1 ice breaker

5 patrol crafts

1 cruiser (old type) Tokiwa

Garrison troops

8 seaplanes, 8 medium and 24 torpedo bombers

Chinhae area

48th and 49th Minesweeper Divisions (2 or 3 minesweepers each)

2 small minelayers

Garrison units

25 fighter planes and 25 medium bombers

In the event of war with the Soviet Union this was the force available to protect the waters of the Japan Sea and the northern area. Its total strength, other than garrison forces, was the old type cruiser Tokiwa, one destroyer, thirty patrol crafts, two submarines, twelve minesweepers, two small minelayers one icebreaker and a small air force of 170 combat planes. This was the situation

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when at 0001 hours, 9 August 1945, the Soviet Union declared war on Japan.

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CHAPTER II

Operations Against the Soviet Union

By the summer of 1945 the war in the Pacific was growing more and more unfavorable to Japan; therefore, the Supreme Command decided to terminate the state of hostilities. On 13 and 21 July 1945, the Imperial Japanese Government requested the Soviet Union to act as mediator, but unfortunately the Potsdam Conference was then in session and no reply was received from the Soviet Government. On 26 July, the Potsdam Declaration, signed by the United States, Great Britain, and China, was announced. The lack of signature by the Soviet Union and its failure to reply to the request for mediation was interpreted to mean that there was still hope of Soviet mediation.

Soviet Declaration of War

At 0001 on the 9th of August 1945, the Japanese Ambassador in Moscow was informed that a state of war existed between the Soviet Union and Japan. The reasons for this unexpected announcement were outlined in the text of the Soviet declaration of war:

With the defeat of Hitler's Germany, Japan has become the only major nation which insists on continuing the war. The demand made by the United States, Britain and China on 26 July, for the unconditional surrender of the Japanese armed forces has been rejected by Japan. Therefore, the proposal submitted by the Japanese Government to the Soviet Union concerning mediation in the Par Eastern War has lost all foundation.

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In view of Japan's rejection of the surrender, the Allied countries have proposed that the Soviet Union expedite the end of hostilities and lessen the number of victims by participating in the war against Japanese aggression.

To procure universal peace for the Allied countries as early as possible, the Soviet Government, as a matter of duty, accepted the proposal of the Allied countries and took part in the Allied declaration of 26 July of this year. The Soviet Government considers that this Soviet policy will accelerate the restoration of peace and save various nations from further sacrifices and suffering, and that this is the only way in which the Japanese people will be enabled to avoid the destruction which was suffered by Germany after she rejected the offer of unconditional surrender.

In view of this point, the Soviet Government declares that the Soviet Union enters into a state of war with Japan tomorrow, 9 August.

Countermeasures

Japan was not in a position to issue a declaration countering that of the Soviet Union which was announced on 9 August, nor did Japan intend to change the operational policy which placed the United States and Great Britain as Japan's foremost enemy. It was expected that war with the Soviet Union would, for some time, be unfavorable on the Asiatic mainland as well as in some island areas, but it was hoped that the units stationed in the areas would put up a good fight. The most important problem was the extremely obstinate attacks on the Homeland by Allied task forces. Although the expected strategic attacks on possible landing beaches were not conducted, it was not possible to determine whether there were any signs of potential enemy landings on the Homeland. Opera-

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tions by the Soviet Union were expected only in the form of air attacks against the Homeland and it was believed that the Soviet forces would not launch a landing operation. Therefore, the Pacific front remained the operational front for the mainland forces.

With the declaration of war on Japan, the Red Army crossed the Manchurian border and, as ordered by Imperial General Headquarters, the Kwantung Army engaged in defensive operations. However, because they were greatly outnumbered, the effort was futile. Two forces, one advancing westward from the direction of Vladivostok and Khabarovsk in the east and the other advancing southward from the direction of China in the northwest, launched a rapid drive toward Harbin. An element struck from the direction of Blagoveshchensk and another element seemed to be about to advance on North Korea. The enemy air forces raided Harbin and Kirin in Manchuria and also gave direct support to the forces which had crossed the frontier.

On 11 August 1945, the Chief of the Navy Section, Imperial General Headquarters, issued Navy Order No 45, directing operations against the Soviet Union be put into effect in accordance with previously issued orders (see Appendix III). At the same time, in anticipation of a Soviet invasion of North Korea, the Naval Special Base Force, which had been deployed from Rashin to Genzan (Najin to Wonsan, Korea), was placed under the command of

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the Kwantung Army. The commander of the Kwantung Army was the supreme commander of ground operations in North Korea, and this Navy unit was transferred to his command to assist in ground operations. Because of the strong possibility of Soviet ships operating from Vladivostok and dominating the Japan Sea and the waters near the Homeland, the Commander-in-Chief of the Navy General Command ordered approximately 30 special attack planes be sent to bases in the Hokuriku (Northern Japan) area or, depending on the circumstances, to the Genzan base. He further ordered that enemy vessels operating in these areas be destroyed through close cooperation with search planes. However, before these orders could be carried out they were canceled by Imperial Decree to the effect that all positive operations would be suspended effective 14 August 1945 until further notice.

At about 0920 hours on 9 August, Escort Ship No 87 and the Yashiro were about to enter the port of Yuki (Unggi) when they were attacked by more than 50 Soviet aircraft. A little later, at about 1000 hours, these same ships were again attacked by about 30 aircraft and suffered some damage due to near misses. On the same day, Soviet planes destroyed three transports off the coast of North Korea and sank three small ships off the coast of South Korea.

On the night of 10 August, seven ships, probably warships, were seen off the coast of Ambetsu on the west coast of Sakhalin. On the night of the 11th, Ambetsu was shelled by several Soviet

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submarines and picket boats, and at 0810 hours on the 12th about 300 Russian troops landed in the vicinity of Ambetsu. At about 0700 hours on the 13th, after the shelling by two or three submarines and one or two destroyers had neutralized Esuforu on the west coast of Sakhalin, 800 Russian troops larded there. The above area was lacking in defensive strength and there were no naval units in that area.

In the Kuriles, Soviet ships, presumably cruisers and destroyers, were observed in action around Onnekotan Island on the 12th, and on that night of the same day Matsuwa Island and Suribachi on Paramushiro Island were attacked by Soviet vessels.

It seems that several cruisers and destroyers attacked Shimushu Island after the 13th and that Russian troops were landed. Fierce fighting was going on in that area on the morning of 18th and four Shimushu-based "Tenzan" torpedo planes made six sorties against the force around Shimushu Island with some success. The Shimushu Naval Garrison Unit, under the command of an army commander, faced the enemy with the strength of one and a half battalions and put up a good fight.

Even at the time of this writing the situation in the North Korea area is not clear. It seems that at about 1100 hours on 12 August the enemy commenced landing in the Rash in (Najin) area. On the evening of the same day, four ships, which appeared to be cruisers, were seen cruising off Seishin (Chongjin). At dusk on

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the 14th, the enemy seems to have commenced attacking Seishin (Chongjin), but details are unknown.

In Manchuria, the Soviet Army advanced at a considerable speed. The Kwantung Army in each sector engaged in fierce fighting, but the general situation remained unchanged. In this sector, enemy action continued for a considerable period of time after the Japanese had ceased hostilities.

Following the issuance of the Imperial Rescript terminating the war on 15 August, hostilities were gradually suspended in each sector. Japan's defense against the Soviet Union came to an end without entering various planned phases of warfare, and all the forces surrendered in each sector as directed by the order to suspend hostilities.

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APPENDIX I

Operational Policy in the Event of War with the Soviet Union During the First Phase Operations

1. Operations against the United States, Great Britain and the Netherlands will be continued in accordance with established operational plans.

2. Operational policy of the Combined Fleet will be as follows:

a. In the event of war with the Soviet Union during the course of the First Phase Operations, the Fifth Fleet, reinforced by the light vessels of the inner combat forces, will assume a defensive role, maintaining the security of our main coastal supply routes and the air defense of strategic points. Later, as soon as the situation in the Southern Operations will permit, light vessels of the Combined Fleet, as well as air units, will be committed and operations against the Soviet Union will be intensified.

b. In the event of war with the Soviet Union after the successful completion of the First Phase Operations, the bulk of the Fifth Fleet, reinforced by elements of the light vessel force and additional air units, will be committed to operations against the Soviet Union. After effecting the speedy reduction of the Soviet Fleet in the Orient, supremacy in the waters off the eastern coast of Soviet territory will be maintained, and, in cooperation with the Army, enemy air strength in the Maritime Province

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and Ussuri areas will be destroyed and Vladivostok and other strategic points in Soviet territory will be occupied.

3. Operational policy of the China Area Fleet will be as follows:

a. With a force consisting primarily of the First and Third China Expeditionary Fleets, Army units being committed from north and central China will be supported and naval escort will be provided for Army surface transportation.

b. Forces under the command of the China Area Fleet will be deployed appropriately.

4. Operational policy for naval districts and naval guard district forces will be as follows:

a. Yokosuka, Kure, Sasebo and Maizuru Naval District Forces; and Ominato, Chinhae and Port Arthur Guard District Forces will intensify their patrols, particularly against Soviet submarines and aircraft, and if hostile craft are sighted in the vicinity of their respective area of jurisdiction, they will be destroyed.

b. In case the outer combat forces launch positive operations, the air units and other required forces of the inner combat forces will be concentrated at the necessary sectors and will support the operations.

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APPENDIX II

Naval Operational Policy to be Followed by the Combined Fleet in the Event of War with the Soviet Union During the Third Phase Operations

1. Initial Operations

a. At the outbreak of hostilities, the bulk of our carrier air strength, reinforced by an element of the land-based air force, will destroy the enemy air strength in the southern Maritime and Kamchatka areas. Every effort will be made to strike the first blow. When this mission has been completed, the enemy fleet in the eastern waters off the coast of the Soviet Union will be destroyed. The air attack on the Kamchatka area may, depending on the circumstances, be made in coordination with the Army.

b. At the outbreak of hostilities, Okha, Petropavlovsk and possibly Sovetskaya Gavin, will be invaded by Army forces with the support of a naval force built around the Fifth Fleet. Concurrently the enemy fleet operation in the Okhotsk Sea and in the Aleutians will be contacted and destroyed.

c. An element of the submarine forces is to attack enemy shipping in the Aleutians and off the coast of Alaska, thereby disrupting shipping and interfering with communication between the United States and the Soviet Union.

d. The remainder of the forces held in reserve will meet any enemy offensive and will destroy the enemy force by assuming a defense with offensive tactics. In accordance with

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the basic policy, operations against the Allies are to continue to have priority.

2. Subsequent Operations

a. The Fifth Fleet, reinforced by an element of the land-based air force, will secure the supremacy of the air and sea in the area west of the Aleutians. In addition, the defenses of occupied areas will be strengthened and the timely invasion of Vladivostok will be carried out in cooperation with the Army.

b. The initial operations will be continued by the remaining forces and, if possible, positive offensive operations will be launched against the Allies.

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APPENDIX III

Operational Policy for Urgent Naval Operations in the Event of War with the Soviet Union in the Course of Operations against the United States, Great Britain and China

1. By means of flexible and tenacious operations and by closely cooperating with the Army, the Japanese territories south of Japan Proper (including Korea) and strategic positions in Manchuria, Hokkaido, Kuriles and southern Sakhalin will, at least, be secured. By controlling the Korea Strait, Tsugaru Strait and Soya Strait, movement of enemy vessels will be disrupted and our main surface supply routes will be secured. However, the above operations will be carried out in a manner which will not interfere with operations against the United States.

2. As a general rule, only necessary air defense will be undertaken and no special air offensive operations will be conducted. However, timely surprise attacks may be launched.

3. Strict patrol will be maintained against raiding enemy vessels and efforts will be made to check their activities.

4. By making defensive preparations at potential enemy landing areas, in coordination with the defending Army units, the enemy advance will be checked.

5. Communication between the United States and the Soviet Union will be disrupted.

6. Operations against the United States, Great Britain and China will be continued generally in accordance with the existing operational policy.

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