Since the mid-1950s., The United States have been actively used for strategic reconnaissance over the territory of the USSR automatic drifting balloons (ADA). They were a shell of a thin plastic film to a volume of several hundreds of thousands of cubic meters, filled, typically with helium, with a special equipment attached to the containers. The first "swallows" were designed to study the velocity and direction of air currents in the sky of the USSR. These flights have shown that using gratuitous wind energy can easily penetrate the "iron curtain" and cross the entire vast country. Soon ADSs began to run in small groups and then mass groups mainly from the US Northern European Allies. Went continuous improvement themselves ADSs and the application of tactics: to increase the height of flight and radio transparency, reduced film thickness (up to 5 micrometers), increased vitality through the use multishell structures and pendants with whole "garlands" of containers, in practice includes equipping balloons jamming guns and launch of the "balls dummy" distracted air defenses.