NECESSITY FOR RECONNAISSANCE 4. The attached graph+ shows the course of the Japanese oil position according to various hypotheses. It is clear that unless the maximum achievement is attained the position will remain critical for some time. Reconnaissance is necessary:(a) to find out if the Japanese have reached the very high rate of development with which we have credited them, (b) to show at what points there is activity which might be interrupted by attack. 5. It is recommended that the reconnaissances should be made with the least delay, not only because the oil supply position is reaching its most vulnerable level, but also because the weather becomes less suitable for photographic work from the end of September onwards.