Foreign Relations of the United States, Conferences at Washington and Quebec, 1943

J.C.S. Files

Report by the Combined Intelligence Committee¹

secret
Enclosure to C.C.S. 127/3

[Quebec,] 16 August 1943.

Scale of Attack on the East and West Coasts of North America

statement of the problem

1. The Combined Chiefs of Staff have directed the Combined Intelligence Committee to report on the probable scale of attack that might be expected on the east and west coasts of North America.

discussion

2. The probable scale of attack on the east coast of North America is discussed in Enclosure “A”; that on the west coast in Enclosure “B”. In this paper, consideration is limited to the Atlantic Coast north of the Straits of Florida and to the Pacific Coast north of Mexico.

conclusions

3. East coast of North America. Submarine attacks on shipping and minelaying in the coastal zone are continuing possibilities. Sporadic bombardment of shore installations, or landing of commando raiders or saboteurs by submarines are also possible but only on a small scale. Similar attacks by surface raiders are possible, but highly improbable. Air attack, on a very small scale, is possible, but is even more improbable than surface attack.

4. West coast of North America. Our conclusions are the same as those for the East coast, with two slight shifts of emphasis:

a. The maximum possible scale of submarine attack is less.

b. The possible scale of attack by ship-borne aircraft is greater. Such an attack, however, is very unlikely.

Enclosure “A”

Scale of Attack on the East Coast of North America

5. Enemy capabilities are virtually limited to attacks by submarine or surface raider. Land-based air attack is impractical. Surface raiders might launch ship-borne aircraft. Both submarines and surface raiders might

a. Attack shipping off the coast,

b. Mine coastal waters,

c. Bombard shore installations (including attacks by ship-borne aircraft),

d. Land commandos,

e. Land trained saboteurs and materials for sabotage,

6. Attacks by any type of aircraft are extremely improbable. Land-based air attack is physically possible, but because of range limitations would involve the sacrifice of the aircraft used and their crews and could not be carried out on a scale which could exert any material effect on the outcome of the war. An attack by ship-based aircraft would offer less physical difficulty, but would be very limited in its maximum scale. The one German aircraft carrier, Graf Zeppelin, has been laid up and there is no indication that she will be available for service in the near future, if ever. Lacking an aircraft carrier, only catapulted planes or seaplanes could be used. The vessels transporting the planes would be subjected to a serious risk of loss. The possibility that Germany would accept these risks appears to be increasingly remote.

7. Operations by surface raiders of any type against sea communications within the coastal zone or against shore objectives are extremely unlikely. A merchant ship raider would probably have a better chance than a warship of reaching undetected the shipping lanes in the coastal zone or a shore objective. The chances of reaching the shipping lanes in the coastal zone are better than those of penetrating within effective gun range of a shore objective. It is most unlikely that either type, if at large in the North Atlantic, would attempt operations against objectives within the North American coastal zone in preference to attack of shipping on the ocean routes. Any relaxation of patrol activities would probably be taken advantage of by submarines rather than by surface vessels.

8. Attacks by submarines. Some 200 German and 40 Italian submarines are believed to be operational. At present, very few are operating immediately off the coast of North America. If, however, a reduction in anti-submarine activity in the coastal zone were perceptible, an increase in submarine activity against shipping in that zone would be likely to occur. Mining, bombardment, and the landing of raiders or saboteurs from submarines are continuing capabilities, but are possible only on a small scale.

Enclosure “B”

Scale of Attack on the West Coast of North America

9. Enemy capabilities are limited to attacks by submarines and surface raiders, the latter ranging in scale up to hit and run operations by a carrier task force. Land-based air attack is impossible so long as Kiska remains effectively neutralized. Japan lacks both the naval strength and the shipping to conduct large scale naval or shipborne attacks against North America.

Both submarines and surface raiders might

a. Attack shipping off the coast,

b. Mine coastal waters,

c. Launch aircraft,

d. Bombard shore installations,

e. Land commandos,

f. Land trained saboteurs and materials for sabotage.

10. Carrier-borne air attack. Japan could form a suitable task force and, considering the vastness of the Pacific, could perhaps bring it undetected within effective range of a profitable target such as Los Angeles–San Diego, the Puget Sound–Vancouver area, or the San Francisco Bay area. The risks, however, would be enormous, and at this juncture Japan cannot afford to risk either carriers or other vessels for indecisive purposes. All such craft available to her are, moreover, required for other uses.

11. Surface raiders. Japan’s shortage of suitable types of naval vessels makes it extremely unlikely that she would employ them as raiders. The shipping stringency would have the same effect as regards armed merchantmen.

12. Submarines. About 60 Japanese submarines are believed to be operational. Some of these are capable of carrying up to 200 men. Japan has tended to use submarines in direct connection with military operations and has not employed them extensively in distant operations against shipping. Submarine attacks on shipping off the west coast of North America, mining, bombardment, and the landing of raiders or saboteurs from submarines are continuing capabilities, but are possible only on a small scale. An increase in the present low scale of submarine operations is possible but improbable. Increasing pressure on Japanese naval forces in the southwest and central Pacific would tend to occupy Japanese submarines in those waters and thus to decrease the probability of their use off North America.

1. Circulated under cover of the following note by the Secretaries of the Combined Chiefs of Staff (C.C.S. 127/3), August 16, 1943: “The attached report on C.C.S. 127/2 [“Scale of Attack on East or West Coasts of North America”, August 6, 1943; not printed], prepared by the Combined Intelligence Committee, is presented for the consideration of the Combined Chiefs of Staff.”

   The report was approved by the Combined Chiefs of Staff at their 118th Meeting, September 10, 1943. See post, p. 1221.