J.C.S. Files

Memorandum by the United States Chiefs of Staff1

Enclosure to C.C.S. 300

Estimate of the Enemy Situation, 1943–44 Pacific–Far East Area (As of 20 July 1943)

1. Basic Factors in the Japanese Situation.

Japan’s basic objective is to establish undisputed control of an area in East Asia and the Western Pacific which shall be militarily secure and as nearly self-sufficient economically as possible. The area now occupied by her approximates the territorial requirements of this objective, but is deficient in three respects, as follows: (1) the possession of eastern Siberia by a latently hostile power; (2) the existence in China of unoccupied areas within bombing range of Japan and of important Japanese communications; and (3) the presence of United Nations forces in the Japanese defensive perimeter in the Melanesia area and the Aleutians. Other territories beyond the limits of present occupation may be objects of ultimate Japanese aspiration, but only those specified are essential to the immediate basic objective.
Relationship to the Axis. Japan’s connection with the Axis is a matter of expediency only. Her action will be coordinated with that of Germany only insofar as she estimates that such coordination will contribute to the realization of her basic objective or—in the long run—to her security.
Relations With Russia. There exists between Russia and Japan a basic conflict of interest. Japan cannot enjoy complete strategic security without gaining control of the eastern region of Siberia. Russia is determined to hold that region, the strategic security of which requires the ultimate expulsion of Japan from the mainland of Asia and from southern Sakhalin. For the present, however, both Russia and Japan desire to avoid war with each other in order to be free to direct their efforts against their respective enemies. Russia is likely to intervene in the war against Japan at some stage, but not before the German threat to her has been removed. After that, she will make her decision in the light of her own interests and will intervene only when she reckons that Japan can be defeated at a small cost to her.
Time. Japan will take maximum advantage of such time as is left to her to consolidate and, if possible, to improve her present position, hoping that, in the eventual reckoning, the United Nations, wearied by the war in Europe and perhaps divided among themselves, will attack her ineffectively or compromise to her advantage. We estimate that from mid-1943 to mid-1944 total Japanese industrial production will increase approximately ten per cent. However, the production of many critical categories—notably merchant ships, aircraft, trucks, and armored vehicles—will increase by more than ten per cent. Japan should expect that ultimatety greatly superior forces can be directed against her.

2. The Existing Overall Situation.

a. General. Japan is on the strategic defensive. We estimate the present strength of her armed forces to be as follows: (1) Naval, 10 B 6 CV, 4 A 14 CA, 16 CL, 81 D 84 S (2) Air, 1400 fighters, 1450 bombers, 850 other types. Of the total, 390 fighters and 120 bombers are ship-based; (3) Ground, 64 divisions, 17 independent mixed brigades, 1 infantry brigade, 3 cavalry brigades, 18 tank regiments and many independent units, totaling in round numbers 3,000,000 men (this total includes naval, ground, and air personnel, but not Puppet Troops).

Japan’s position, facing United Nations forces from the North Pacific around to India, is one of great natural strength but requiring secure and sufficient ocean transport over long lines of communication. At this time, her position in China is secure because of the present inability of either China or the other United Nations to mount large-scale operations there. Russian commitments in Europe and Japanese strength in Manchuria insure for the time being the security of Japan’s northern flank. Japan is able at present to direct her maximum effort toward building up her economic and military strength.

b. Limitations on Japanese Striking Power.

Shipping. The margin of Japanese shipping, after allowing for essential trade and the maintenance of Japan’s many distant overseas commitments, is small and continues to fall. Additional tonnage might still be found for new operations by diverting it from trade, and, provided such diversions were temporary, this need not have serious effects on Japan’s capacity to wage war. Since, however, Japan’s rate of building, though on the increase, cannot keep pace with the present rate of sinkings, she would be reluctant to risk adding further to her shipping commitments or incurring losses such as she would have to expect from any further large-scale sea-borne offensive operations. Although attempts are being made to improve the position by building a large number of small and medium-size [Page 419] wooden ships, the general shipping position is becoming increasingly difficult and may well become precarious in 1944.
The situation in regard to tankers is more critical. Japan is attempting to meet a deficiency in this respect by the use of dry-cargo ships as oil carriers.
Air Power. We believe that lack of sufficient air strength will prevent Japan from engaging in more than one major operation at one time.
Naval Requirements. Japan’s naval strength is adequate for present requirements, but must be carefully husbanded for future decisive action. Her extended lines of communication already entail a large commitment of naval strength for the protection of essential shipping. Their further extension, or indecisive action entailing heavy attrition, might well be unacceptable.
Military Requirements. A large proportion of Japanese ground forces is required for occupational duties and for concentration in Manchuria to balance Russian forces in Siberia. Japan, however, has ample ground forces for any probable combat requirements, inasmuch as the insular character of much of the occupied area and the topography of New Guinea, the Indo-Burmese frontier and China limit the scale of ground operations in those areas. Her ability to move her strategic reserve is limited by shortage of shipping.

3. The Existing Local Situation on Various Fronts.

North Pacific. Japan holds an exposed outpost at Kiska, but will not risk major forces in order to prevent its fall. We believe the Japanese are preparing for a determined defense in the Kuriles.
Manchuria. Japanese forces in Manchuria and Russian forces in eastern Siberia–Outer Mongolia are roughly in balance. Japan has the advantage in strategic position, equipment, and supply, but is deterred from aggression by a healthy respect for Russian armed forces; the vulnerability of Japan to bombing and submarine attack; and the additional strain which such a commitment would impose on her resources in general, including the strain on her shipping.
China (Except Yunnan). The front has been largely stabilized for years, with the Japanese in possession of the country’s principal productive areas and communications lines. The Japanese are deterred from further expansion primarily by logistical difficulties and secondarily by Chinese resistance. On occasion the Japanese engage in minor offensive operations to season inexperienced troops and accomplish limited objectives such as the temporary denial of facilities to the Chinese. Although nominally in overwhelming numerical strength, the Chinese forces are at present so poorly equipped, supplied, and [Page 420] trained that they are unable to prevent these forays or to undertake other than local aggressive action. This Chinese military weakness springs in large part from China’s generally anemic condition, which has resulted from loss of productive areas, disruption of internal communications, isolation from outside support, and war-weariness. Although a formal separate peace is highly improbable, it is possible that, if China’s condition is not effectively relieved, an “undeclared peace” may eventually result.
Yunnan. Active operations are not indicated. The inconsiderable Japanese forces on the Indo-China and Burma frontiers are separated from Kunming by extremely rugged terrain. Malarial conditions in the area would impose a high rate of attrition on any troops operating there.
Burma. The wet monsoon precludes major operations from May to October. Present Japanese strength is sufficient for only local offensive action.
Southwest Pacific. The build-up of ground and air strength in the Timor–Inner Seas area and northeastern New Guinea appears to have been defensive in character. No important ground force movements have occurred since 1 March.
Central Pacific. Of the heavy naval units withdrawn from Truk to Japan at the time of the capture of Attu, some have returned to Truk. Air strength in Micronesia is being reinforced, but attrition and reinforcement are approximately in balance.
Strategic Reserves
Naval. Normally Japan maintains her battleship and carrier strength in home waters and at Truk, shifting the center of gravity according to circumstances. A formidable striking force, which can reach any threatened point of the defensive perimiter in from six to nine days, can be quickly assembled in either of these central areas. However, destroyer shortage is becoming critical.
Air. We believe no strategic reserve exists as such, but Japan’s ability to fly even fighter planes to practically any part of her position enables her to reinforce quickly any threatened front at the expense of other theaters.
Ground. Surplus ground strength in Central China constitutes Japan’s initial reserve. If hard pressed, she can also draw surplus strength from Japan and North China and in extremity from Manchuria.
Puppet Troops.
Manchuria, Strength.
In Manchuria there are reported to be 328,000 Puppet Troops. They are organized both as combat divisions and as garrison troops. [Page 421] Only in recent years have they received automatic weapons and artillery and, in view of apparent Japanese shortages in both these categories of weapons, it is not thought that the puppet units are completely equipped.
Disposition. About 12,000 Manchurian Puppet Troops are reported to be in China, The mass of Manchurian Puppet Troops are stationed along the Siberian border, near the larger cities, and in strategic locations generally but never without sufficient Japanese units in the vicinity to keep them under control.
Effect on Japanese Strategy. In the past the Manchurian Puppet Army has been maintained principally for political reasons, to maintain internal order, and to prevent former soldiers from resorting to banditry. However, in the event the Japanese-Soviet situation remains unchanged Japan may replace two or three of her divisions in Manchuria with Puppet Troops.
(a) China and Mongolia. Strength. At present there are reported to be 366,000 Nanking Government Puppet Troops in China. They consist mainly of numerous small commands readily controlled by the Japanese. There are indications that these troops are now being reorganized into infantry divisions of three regiments each with a divisional strength of about 6,000. It is reported that light artillery and heavier machine guns will now be issued to Puppet Troops whereas these weapons were denied them in the past. Because of the unreliability and defection of Nanking Puppet Troops in the past, we believe that the Japanese will hesitate to increase them beyond 500,000 during 1943–1944. Rather than increase the Nanking Puppets, it is more likely that Manchurian Puppets will be brought south for garrison duties.
(b) Disposition of Puppet Troops. About 209,000 Puppet Troops are located in Central China, 93,000 in North China, 48,000 in South China, and 16,000, mostly cavalry units, in the Chahar–Suiyuan area. Future dispositions will not change radically except that the distribution of new contingents will be influenced by the location of the Japanese troops which they relieve.
(c) Effect on Japanese Strategy. Nanking Puppet Troops have been used as garrison troops for maintaining internal order and have been employed in no offensive to date. We believe that the Japanese may by the end of 1944 further reduce their forces by four divisions in North China and by two divisions in Central China, replacing them with Nanking and Manchurian Puppet Troops. At all times a nucleus of Japanese forces must remain in all strategic centers to keep the Puppet Troops in line.
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4. China.

Strength. While China is reported to have over 300 divisions including Communist divisions, of about 7,000 men each, problems of equipment, training, leadership, supply, and loyalties to local military leaders make it improbable that one-fifth of that number are better than fairly reliable troops capable of defensive operations on any front. Even fewer are sufficiently well equipped, trained, and led to undertake offensive operations. If sufficient supplies get through and the United Nations program for equipping and training some of the Chinese is successful (the 30 division plan), the situation may improve and more of China’s tremendous manpower may be effectively available for United Nations operations. However, it is improbable that the effect of this, at best, could be felt strategically before the summer of 1944.
China’s guerrillas, estimated at some 500,000 men, in addition to many of her divisions are rendering excellent service in compelling Japan to keep a large occupational force in China.
Capabilities. If given adequate United Nations air support China may be able to defend her own strategic areas against anything but an all-out Japanese offensive. If given strong United Nations air support China might be able to execute a very limited objective offensive. It is doubted that she would have the ability to hold such an objective, if attained, against a determined Japanese counter offensive.
Probable Intentions. The Chinese probably intend to remain on the defensive and concentrate on reequipping and retraining their army for offensive action at a later date.

5. Prospective Overall Developments Through 1944.

a. Naval strength. Disregarding attrition, we estimate that Japanese naval strength should increase as a result of new construction, as follows:

15 June 43 10 6 4 14 16 81 84
1 Nov. 43 12 8 7 16 18 93 102
1 May 44 13 10 10 18 20 105 120

b. Air strength. Aircraft production is expected to continue to increase gradually during 1943 and 1944. Present increase is balanced by present attrition.

c. Ground strength. It is expected that by the end of 1944 the strength of the Japanese army will have increased to 72 divisions and 14 independent mixed brigades, three cavalry brigades, and 20 or more tank regiments.

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d. War production. During 1944 Japanese munitions and other war production is expected to show a substantial increase over 1943, provided that ocean shipments can be maintained and that industrial plants escape bombing. The overall rate of industrial production may increase by about 10 per cent. In addition to overall increased production, Japan is continuing to develop uneconomic production of materials in the “Inner Zone”* (such as oil, coal, iron, aluminum) for strategic reasons. This work should be well advanced by the end of 1944.

e. Shipping. Despite Japan’s strenuous shipbuilding efforts estimates of the rate of loss and rate of construction of steel ships indicate that the Japanese may suffer a net loss of 1,500,000 G.R.T. of steel operating tonnage from 1 June 1943 to the end of 1944. However, construction of wooden vessels and further substitution of land transport may offset a part of the estimated net loss of steel ships.

f. Morale. Japanese morale will remain high until, through an effective attack on vital areas or a major defeat which cannot be concealed, faith in their leaders has suffered severe impairment.

6. Forecast for 1944.

General. Japan will probably remain on the strategic defensive except in one or more of the following circumstances: (1) if convinced that Russia had decided to attack her or to grant to the other United Nations the use of Siberian air bases, Japan would strike first; (2) if convinced that there was real danger of serious United Nations operations against her from China, Japan would strike first; (3) if Japan had inflicted a severe defeat upon United Nations forces operating against her in the Pacific, she might follow up offensively; (4) if Russia met with serious reverses on the Western Front, Japan might take the opportunity to attack the Soviet.
North Pacific. We believe that Japan will continue to strengthen her defenses in the Kuriles as means become available, but is not likely to depart from the defensive except in case of war with Russia, in which case she would probably try to seize Kamchatka.
Manchuria. We believe that Japan will continue to seek to avoid war with Russia in all circumstances except those indicated in a(1) above. She will continue to match Russian strength in Siberia, reducing her forces in Manchuria only in case of extreme necessity.
China (including Yunnan). We believe that Japan will continue to seek a satisfactory solution in China by political means, but will probably engage in no decisive military operations there except in the circumstances indicated in a(2) above. In that case, her most likely [Page 424] objective would be Kunming and probably the determining factor would be relative air strength there.
Burma. We believe that Japan will remain on the strategic defensive.
Southwest and Central Pacific. We believe that Japan will remain on the strategic defensive, continuing to build up her local defensive forces and facilities and her naval striking force.
  1. Circulated under cover of the following memorandum by the United States Chiefs of Staff (300), August 6, 1943: “The U.S. Chiefs of Staff submit herewith an estimate of the enemy situation, 1943–44, Pacific–Far East Area for consideration by the Combined Chiefs of Staff at the Quadeant Conference.”
  2. Japan Proper, Korea, Manchuria, North China, Formosa, and Karafuto (Japanese Sakhalin). [Footnote in the source text]