The British Ministry of Defence is releasing a study which finds that most, if not all, UFO sightings can be fully explained by natural phenomena, such as meteors, airplanes, weather, and so on. In other words, this 400+ page report concludes that there is no strong evidence that any UFOs are actually alien spacecraft.
As an astronomer, we are often asked about aliens and UFOs. And, to be honest, I don't know if extraterrestrial intelligence exists or not. But I feel pretty confident that alien spacecraft are not visiting the Earth. The challenges to long-distance space travel are far, far greater than most of us can imagine.
But I applaud the ministry for publically releasing their study. The U.S. Armed Forces have also studied the UFO phenomenon, but have not released their study. Personally, I would guess this is because many UFOs are military aircraft, both known and unknown. But this is just a guess. And, since the US does not release its studies, people continue to assume it must include aliens.