The MUOS (Mobile User Objective System), a radar installed in Sicily just inside the reserve "cork-forest of Niscemi", is one of four watchmen of the global system that the US Navy has designed in the various corners of the world to keep an eye on all over the planet. The history of this installation is made of broken promises, political interventions pro Muos then disavowed by the judiciary, protests organized in an effort to speak with those powers, who also had seemed willing. At the basis of the "NO Muos" movement's actions, here you are remembered with a similar case, Vatican Radio, which at the beginning of this century shook the Italian political world, and behind the request to apply the "precautionary principle" there is a clear concern: "Do the high-frequency electromagnetic waves hurt"? To provide a scientifically based answer to this question, after a quick recap of the physical principles, it is made clear why it is legitimate to speak of "electrosmog" and how misleading have been, and are up to now, some statements "reassuring" about the evolutionary equilibrium with the non ionizing radiation.