 Complete the following phrase:  Beginning with Italy in 1927, several countries experimented with using parachutes to drop soldiers behind enemy lines. The regular Soviet Airborne Troops were established as early as 1931 after a number of experimental military mass jumps starting from August 2, 1930. Earlier the same year, the first Soviet mass jumps led to the development of the parachuting sport in the Soviet Union. By the time of World War II, large airborne forces were trained and used in surprise attacks, as in the battles for 