500.A15A3 Construction/131
The American Ambassador in Japan (Grew) to the Japanese Minister for Foreign Affairs (Hirota)
Excellency: The Japanese Government will be aware that under the London Naval Treaty 1936 the American Government is precluded from constructing capital ships (i. e., vessels of more than 10,000 tons standard displacement or with a gun of more than eight inches) which exceed 35,000 tons or carry a gun of more than 16 inches, or which are of less than 17,500 tons or carry a gun of less than 10 inches. As regards cruisers (i. e., vessels of not more than 10,000 tons with a gun of not more than eight inches) the American Government is limited to a maximum of 8,000 tons with six inch guns.
The Japanese Government has unfortunately not seen its way to subscribe to the London Naval Treaty, nor has it hitherto felt able to give any assurances that Treaty limits would in practice be adhered to by it.
As the Japanese Government will be aware, the Naval Treaty gives [Page 304] the American Government a right of escalation in the event of building not in conformity with treaty limits by a Power not a party thereto. There have for some time been persistent and cumulative reports, which, in the absence of explicit assurances from the Japanese Government that they are ill-founded, must be deemed to be authentic, that Japan has undertaken or intends to undertake construction of capital ships and cruisers not in conformity with the above-mentioned limits. The American Government has therefore decided that it will be necessary for it to exercise its right of escalation unless the Japanese Government can furnish the aforesaid assurances and can satisfy the American Government that it will not, prior to January 1, 1943, lay down, complete, or acquire any vessel which does not conform to the limits in question, without previously informing the American Government of its intention to do so and of tonnage and calibre of the largest gun of the vessel or vessels concerned.
In view of the forthcoming publication of naval estimates and necessity for giving other Treaty Powers information as to intended American construction, the American Government will be glad to receive a reply not later than February 20 next. Should no reply be received by that date, or should the reply be lacking in the desired information and assurances, it will be compelled to assume that the Japanese Government either is constructing or acquiring or has authorized the construction or acquisition of vessels not in conformity with the limits referred to. The American Government would thereupon be obliged in consultation with the other Naval Powers with which it is in treaty relations to resume full liberty of action. If, however, the Japanese Government, though engaged in, or intending to engage in, construction not in conformity with treaty limits, were willing to indicate forthwith the tonnages and calibres of guns of the vessels which it was constructing, or was intending to construct, the American Government for its part would be ready to discuss with the Japanese Government the question of the tonnages and gun calibres to be adhered to in future if Japan were now prepared to agree to some limitation. It would, however, be necessary that such consultation should be completed by May 1.44
I avail myself [etc.]
- The date was advanced to April 1 by the Department’s telegraphic instruction No. 49, Feb. 9, 1938; not printed.↩