My biggest question when I see statements about these UFOs being aliens is “Where is the mother ship”? The constraints on something built to operate in the Ear

My biggest question when I see statements about these UFOs being aliens is “Where is the mother ship”? The constraints on something built to operate in the Earth’s atmosphere are much different than a ship that can actually cross interstellar distances. So if we are seeing the equivalent of alien fighters (small, fast, highly maneuverable) there should also be the equivalent of an aircraft carrier which provides the long distance transport and logistics for these fighters.