Why Kimmel searched the southwest approaches

Edwin Layton had studied Japanese in Tokyo, worked as a codebreaker, and became Kimmel's chief intelligence officer. Kimmel recommended him to Chester Nimitz, and Layton later defended the southwest search as the logical use of the reconnaissance resources and intelligence then available. Traffic analysis pointed toward Japanese submarines and at least one carrier division in the Marshall Islands, while Kimmel received no warning of a carrier threat approaching from the north. His aircraft could properly cover only a narrow sector. Concentrating the search southwest was therefore a rational use of scarce assets within the intelligence picture supplied to Hawaii. A larger reconnaissance force, or accurate information about the missing carriers, would have changed the operational choices open to the fleet commander.