War Department
                                           Washington, February 7, 1941.
 
                                     SECRET

Subject: Air Defense of Pearl Harbor, Hawaii.

To: The Secretary of the Navy.

1. In replying to your letter of January 24, regarding the possibility of surprise attacks upon the Fleet or the Naval Base at Pearl Harbor, I wish to express complete concurrence as to the importance of this matter and the urgency of our making every possible preparation to meet such a hostile effort. The Hawaiian Department is the best equipped of all our overseas departments, and continues to hold a high priority for the completion of its projected defenses because of the importance of giving full protection to the Fleet.

2. The Hawaiian Project provides for one hundred and forty-eight pursuit planes. There are now in Hawaii thirty-six pursuit planes; nineteen of these are P-36's and seventeen are of somewhat less efficiency. I am arranging to have thirty-one P-36 pursuit planes assembled at San Diego for shipment to Hawaii within the next ten days, as agreed to with the Navy Department. This will bring the Army pursuit group in Hawaii up to fifty of the P-36 type and seventeen of a somewhat less efficient type. In addition, fifty of the new P-40-B pursuit planes, with their guns, leakproof tanks and modern armor will be assembled at San Diego about March 15 for shipment by carrier to Hawaii.

3. There are at present in the Hawaiian Islands eighty-two 3-inch AA guns, twenty 37 mm AA guns (en route), and one hundred and nine caliber .50 AA machine guns. The total project calls for ninety-eight 3-inch AA guns, one hundred and twenty 37 mm AA guns, and three hundred and eight caliber .50 AA machine guns.

4. With reference to the Aircraft Warning Service, the equipment therefor has been ordered and will be delivered in Hawaii in June. All arrangements for installation will have been made by the time the equipment is delivered. Inquiry develops the information that delivery of the necessary equipment cannot be made at an earlier date.

5. The Commanding General, Hawaiian Department, is being directed to give immediate consideration to the question of the employment of balloon barrages and the use of smoke in protecting the Fleet and base facilities. Barrage balloons are not available at the present time for installation and cannot be made available prior to the summer of 1941. At present there are three on hand and eighty-four being manufactured-forty for delivery by June 30, 1941, and the remainder by September. The Budget now has under consideration funds for two thousand nine hundred and fifty balloons. The value of smoke for screening vital areas on Oahu is a controversial subject. Qualified opinion is that atmospheric and geographic conditions in Oahu render the employment of smoke impracticable for large scale screening operations. However, the Commanding General will look into this matter again.

6. With reference to you other proposals for joint defense, I am forwarding a copy of your letter and this reply to the Commanding General, Hawaiian Department, and am directing him to cooperate with the local naval authorities in making those measures effective.

 
                                                    /s/ HENRY L. STIMSON
                                                       Secretary of War.
 
Page 564
 
                        Memorandum Endorsement
 
                                     NAVY DEPARTMENT, February 13, 1941.
Op-30B-AJ
(SC)A7-2(2)/FFI
D-27446
 
From: Director, Naval Districts Division.
To: Director, War Plans Division.
Subject: Air Defense of Pearl Harbor, Hawaii. (SecWar ltr, of Feb. 7,
         1941 to SecNav.)

1. Returned. It is recommended that a copy of the subject letter be sent to the Commander-in-Chief, U. S. Fleet and the Commandant of the 14th Naval District.

 
                                                         /s/ Alex Sharp,
                                                             ALEX SHARP.
(Pencil Notation: Done 015712 of 11 Feb. M.)