TOP SECRET It is also probable, and follows from the assumption made in Para. 6, that information regarding the probable build up of Soviet Land Forces for an invasion of this country would be obtained by SACEUR; but since this cannot be certain, some provision is clearly necessary for photographic reconnaissance relating to the build up of Soviet Land Forces; but it is clear that, at the very beginning of a war, it must take second place to intelligence relating to the air battles. 10. It has been appreciated* that the main attack an our sea communications will probably take the form of attacks on ports by bombing, mining and sabotage, and that, on the outbreak of war the maximum enemy effort against our sea communications may be devoted to their submarine and mining offensive.