From Radetzky to the Japanese, the balloon as a weapon: a radar-proof trick

In an era of drones, cyber-attacks and hi-tech devicesAmerica’s oldest flying weapon awakens fears: a hot air balloon, which has been hovering undisturbed in the skies of the States for three days. A high-altitude spy of surprising simplicity and effectiveness, capable of crossing continents by riding the currents to collect top secret information. What it does is not clear, it probably captures data on radar frequencies and transmits them to satellites: it carries out the same intelligence work done by US satellites which cost billions for a minuscule expense.