5.    These difficulties do not apply so strongly to a small
scale raid-
ing force escorted by cruisers and aircraft carriers which-have much
greater endurance. For this reason it is necessary to take into account
the possibility that a force compr, ising 10-15 fast merchant ships
carrying up to '.2 brigades on a low scale of transport might undertake
a destructive raid.
 
NAVAL BOMBARDMENT.
 
         6. For the reasons given above, the employment of enemy
battleships any great distance to the eastward of 'Hawaii is
improbable, iNaval bombardment of important objectives on the west
coast of North America is therefore likely to be restricted to
bombardment by armoured ships other than ships of the line and
cruisers.
 
CARRIER-BORNE AIR ATTACKS.
 
        7.    The employment of a carrier force escorted by cruisers
for the air attack of important naval and industrial objectives is the
most probable
threat which 'has to be met. It is considered that the Japanese could
make
available a force of from ~2-3 aircraft carriers escorted by 4
cruisers, without interfering with 'her dispositions for the other
operations upon which she
is .now engaged. This would involve an attack by some 80-100 dive
and/or torpedobombers, with ship escort of approximately 24 fighters.
 
MINE-LAYING IN PORTS AND THEIR APPROACHES AND ATTACKS BY HUMAN
TORPEDOES.
 
        8.    Mine-laying by raiders and submarines in coastal waters
must be ex-
    pected. 'The enemy's ability to carry out attacks by 'human
torpedoes 'has, .it is understood, been demonstrated at 'Hawaii. lit
cannot therefore be .ignored.
 
CONCLUSIONS
 
                 So .long as the United 'States maintains a battle
fleet in the Pacific, large scale seaborne expeditions against the
western seaboard of North
    America and the employment of capital ship forces in this area are
considered ~impracticable. The most probable enemy threat .is
carrier-borne air attacks
    and sporadic naval bombard]nent, but a small scale destructive raid
cannot be .ignored. In'view of the great distances Over which 'these
operations would
z have to be undertaken, it .is probably .not necessary to prov. idea
strong scale of defense except at selected points of great importance,
which can be cOvered by the normal form of coast and air defense
supplemented by mobile land and air striking forces.
 
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