My summary of the UFO alien situation is that they are either inter-dimensional or extra-dimensional objects, like ghosts, that can appear or disappear, pass through solid matter, walls, mountains or sea, whenever they want. Alternatively they are within our dimension but use the Einstein-Rosen bridge principle enabling time and space to be bent and travel by wormholes instantly (but using immense energy) wherever they desire. This would answer people who say that travelling here from nearby stars or distant galaxies would take an unbelievable time.
Many types of UFOs and aliens have been reported during thousands of years, increasing since 1940s when we started exploding nuclear bombs and endangering our existence and ruining the earth’s environment. This demonstrates that they may be here to watch our development and may be considering how to change our way of life, for instance by changing our DNA, or even exterminating humans, or just offering us advice and technical assistance to help solve the current problems. We just don’t know what they intend unless they really have had contact with our leaders like president Eisenhower.