As a rule, if a pursuit plane attempts to attack an UFO, it brings no damage to it

The first attempt to destroy an unidentified flying object was officially registered in October of 1944 in Europe. US Air Force pilots encountered several ball-like UFOs in the airspace. Pilots decided that they saw new secret Nazi weapon, which was rumored a lot back in those days. Americans opened fire on those balls, although no bullet managed to cause any damage to them.