Memorandum by the Japanese Naval Experts

1. At the Second Plenary session of the Conference, Baron Kato, as Plenipotentiary Delegate for Japan, expressed his approval of the American proposal in general, and made a declaration of his determination to carry out a drastic reduction in naval armaments. At the same time, he stated that, in making a more detailed study of the proposal, it would be necessary to take into consideration the question of national security and that certain modifications in tonnage basis will be proposed later.

At the first meeting of the sub-committee on Limitation of Armaments,63 the Chief of the Japanese Naval Experts, acting under instruction of Baron Kato, declared that the ratio of 70 per cent for Japan is deemed absolutely necessary. This demand, we believe, is in accord with the spirit of safe-guarding the interests of [Page 70] all concerned, as expounded in the Preamble of the original Hughes proposal.

Subsequently, at a meeting of three delegates representing Japan, United States and Great Britain, Mr. Hughes argued that the ratio of 5, 5, and 3 is based upon existing strength and that any modification will mean destruction of the original proposal. In response Baron Kato stated that it would not be possible for him under any circumstance to set aside the principle of national security. To facilitate progress of the Conference, however, he suggested that the experts of the three nations should be instructed to exchange with each other the results of their investigations concerning existing strength, and to make a most careful study from purely technical viewpoint. It was in this manner that these meetings have been called, and consequently it must be understood that the main contention of Japan for the minimum of 70 per cent, based upon her national security, is not to be affected by any result of these meetings.

2. Concerning the term “existing strength,” there is no common definition among the different navies. In order to calculate the existing strength, therefore, it is necessary, first of all, to define the exact meaning of this term; otherwise it would be quite useless to argue concerning correctness of any calculation. For this reason Japan has asked American experts, time and again, for a definition of existing strength, but, to their regret, the American replies failed to define the term and gave simply the method by which their calculations were made. The reply of the American expert[s] was that according to their viewpoint, the existing strength is measured by the tonnage of dreadnaughts, built and building. On the other hand, the Japanese experts hold that by existing strength is meant the naval force now in being and in existence, and that it is impossible to recognize as existing strength the uncompleted ships, which are unfit for navigation and naval battle, and which have no capacity for rendering account as fighting units.

Japan greatly appreciates the sincerity of the United States, manifested by her willingness to sacrifice great expenditures by scrapping her ships under construction. It is for this reason that Japan has joined most heartily to make the great sacrifice of scrapping her own ships under construction. But the opinion of the American experts, that these sacrifices should be taken into consideration in calculating the existing strength, is opposite to the opinion held by the Japanese experts. It is true that there are some differences, also, in minor elements, but the chief factor affecting the final result lies on this point. So long as such wide differences [Page 71] exist in their fundamental viewpoint, it would be absolutely impossible to arrive at an agreement in their calculations.

3. According to the opinion of Japanese experts, there are three methods of calculating existing strength, and the following are the results:

(For details, see the separate table64).

U. S. A. Japan
Japanese classification American classification
(1) Pre-Dr.
100% 76% *69%
(2) Dr.
100% 70% 67%
(3) Sup.-Dr. 100% 86% 86%

Note: If battleships of over 20 years are eliminated in accordance with Hughes’ original proposal, the Japanese percentage in (1)* will be 68 per cent.

In (1), existing strength is calculated upon the basis of Japanese understanding of the original Hughes proposal, i. e., correct interpretation of Hughes proposal should include Pre-Dreadnaughts in existing strength.

In (2), existing strength has been calculated by eliminating Pre-Dreadnaughts in accordance with American experts’ opinion.

In (3), existing strength has been calculated on the basis of tonnage of Super-Dreadnaughts. The ships with 12″ guns have been eliminated because it is generally recognized by naval experts that these ships are not qualified to be placed in the first line with Super-Dreadnaughts.

In any one of the above calculations, the existing strength for Japan is either about or over 70 per cent as compared with existing strength for United States.

Japanese naval experts are convinced that the existing strength for Japan is easily over 70 per cent in view of the fact that their super-dreadnaughts possess strength of 86% as compared with those of the United States.

4. In summing up: The ratio of 5, 5, and 3, as proposed by United States represents simply the figures calculated by American experts according to their own view-point. According to the calculations of [Page 72] Japanese experts, Japan has the strength of about or over 70 per cent. In view of the above, unless it is proved that American basis of calculation is correct and Japanese basis of calculation is incorrect, it would be impossible for the Japanese experts to approve the ratio of 5, 5, and 3, as the correct estimation of existing strength.


Comparison of Naval Strength

United States Japan
Japanese classification American classification Japanese classification American classification
1 Pre-dreadnaughts Dreadnaughts Super-dreadnaughts 33 ships
728,390 tons
39 ships
797,135 t.
25 ships
550,250 t.
25 ships
549,196 tons
2 Dreadnaughts Super-dreadnaughts 20 ships
532,650 tons
18 ships
500,650 t.
13 ships
375,020 t.
11 ships
334,700 tons
3 Super-dreadnaughts 12 ships
365,000 tons
10 ships
313,300 tons
Remarks If battleships of over 20 years are eliminated in accordance with original Hughes proposal, the Japanese percentage in (1)* will be 68%.
  1. With despatch no. 1962, July 31, 1936, the Ambassador in Japan enclosed a translation of note no. 65, July 29, 1936, from the Japanese Minister for Foreign Affairs, containing the following statements:

    • “(1) … at the first naval sub-committee meeting held at the Pan-American Building on November 16, 1921, at 11 a.m., Vice Admiral Hiroharu Kato, chairman of the technical committee, made the following statements:
      • ‘(a) I am of the opinion that a State has an inherent right to maintain armaments for the security of the State itself and for its defense and that these armaments must, in so far as the limits of defensive operations are concerned, be determined by the will and judgment of such State to meet the requirements of its own security.
      • ‘(b) Japan cannot accept a sixty per cent ratio for the reason that with strength of less than seventy per cent she fears for her security and defense.
      • ‘(c) Though the ratio of naval strength of Great Britain, the United States, and Japan be defined, according to the American proposal, at 10:10:6, Japan nevertheless asserts a need of more than seventy per cent, although she does not claim parity with Great Britain and the United States. As regards aircraft carriers, Japan claims parity with Great Britain and the United States for her defense, because of her geographical position and special circumstances.
      • ‘(d) The battleship Mutsu should be preserved because already built.’
    • (2) With regard to the meeting of chief delegates of the United States, Great Britain, and Japan on November 19, 1921, … on the afternoon of November 19, 1921, Vice Admiral Kato, chief delegate of Japan, had an interview at the Department of State with Mr. Hughes and Mr. Balfour in compliance with a request from Mr. Hughes. In this interview, views were exchanged among the three chief delegates over the 5:5:3 ratio but no agreement was reached. Vice Admiral Kato made a reservation as regards the American proposal, and in accordance with the agreed procedure of the Conference he proposed a meeting of experts of the three Powers that they might deliberate upon a method of fixing naval strength through study rather than by negotiation. This proposal was approved by Great Britain and the United States.”

  2. Annex, infra.