During the 1960s, UK Early Warning radar systems picked up a fast moving, medium altitude object heading East over the Irish Sea towards the UK. It was during daylight hours, and a squadron of Royal Air Force BA Lightning F6 Interceptor jets were launched in response to this. These Cold War period fighters, designed as all-weather interceptors, could reach speeds in excess of Mach 2.3 at 40,000 ft, were armed with air-to-air missiles and 30-mm Aden guns, and were considered to be formidable aircraft for the times.
The Lightnings were vectored in on the object, by this time travelling over UK mainland, and they postitioned themselves for intercept. The UFO then came into both visual and radar contact, and was described as a very bright sphere of light, moving horizontally at high speed. As the UFO had failed to respond to any radio signals and was now heading deep into UK Airspace, a decision was taken for the jets to stop the UFO by firing on it. But when the fighters "painted" the UFO with their weapons systems, the UFO simply accelerated away from them at a phenomenal speed, and the Lightnings simply lost it over the North Sea - failing to keep up with it.
And I believe that during the 1970s, several Imperial Iranian Airforce Phantom jets played a game of cat and mouse all one afternoon with a UFO which was buzzing Tehran Airport. No matter what the Phantom pilots tried, the UFO (a bright, fast moving object) outwitted and outflew them all afternoon, backwards and forwards over the Airport runways (LOL).
Incidentally, while it's obvious that UFOs are well equiped to avoid our hostile "overtures" when needs be, I dread to think what their occupants feel about our species' unprovoked attack attempts .... ??