This rate of effort is likely to be directed against the U.K., but the possibility of some diversion to continental targets, e.g. Antwerp, cannot be entirely excluded. The above estimate, however, makes no allowance for Allied counter-measures against the enemy's airfields and transportation system. 12. All large built up areas in the United Kingdom are within range of the aircraft now being used for this purpose. Attacks on many of them, however, would involve substantially increased fuel consumption and the acceptance of greater risks from our fighter defences.