The Japanese, exploiting jet streams (strong air currents at 300km/h at 12,000m altitude from West to East), sent 9,000 balloons inflated with hydrogen and a 15kg explosive bomb towards the United States; approximately 300 landed on national territory but only a very few caused damage, and the press, collaborating with the government, kept the matter quiet, thus causing the Japanese to desist, judging the operation ineffective.
