This chapter discusses the fact that military espionage constituted one of the main activities used in the anti-Cuban project Operation Mongoose. The U.S. intelligence services used the most modern air resources at hand, and from August 1962 the U.S. government ordered an increase in U-2 photographic reconnaissance flights throughout the Cuban archipelago. Cuban authorities publicly denounced the increasingly frequent violations of their country’s airspace. The chapter also stresses that during the fall of 1962 the military situation in the Caribbean was becoming more dangerous. Not far from Cuba, U.S. forces were concentrated under the pretext of carrying out military exercises. In the meantime, in Cuba, the finishing touches were being put on well-rehearsed mobilization plans and troop alerts that specified the combat missions to be carried out by each army unit, the weapons and types of armed forces to be used to fight back the enemy’s marine and air landings and the counterstrikes and counterattacks to be used in order to quickly annihilate any attacking forces that might succeed in landing.