UFOs may exist.
We can never be 100 percent sure what other countries are up to.
And after all of the REALLY WEIRDLY shaped machines we designed to fly in the mid 1950’s, I can see where they would look like nothing seen before.
Forget what show I saw them on but boy we’ve made some odd designs :)
Note most UFO sightings really began to be recorded after the invention during WWII of the turbo jet engine. That engine and the Black Ops (Skunk Works, etc.) are what most people saw or heard from 1947 to this very day.