UFO's were recorded as first being sighted long before WWII. Just in case you'd like to use facts...
Aurora Texas UFO Incident
The Aurora UFO Incident is an alleged UFO crash that occurred on April 19, 1897 in Aurora, Texas. A UFO is said to have hit a windmill resulting in its crash, and the pilot of the UFO was found and buried at an unmarked grave.
Early in the year and throughout the month of April, numerous eyewitness sightings of cigar-shaped airships were reported in multiple locations in Iowa, Kansas, California, Alabama, West Virginia, Texas, Oklahoma, Indian Territory, Nebraska, North and South Dakota, Missouri, and Minnesota.
Battle of Los Angeles
The West coast air raid, sometimes referred to as the Los Angeles air raid or The battle of Los Angeles, was an event which took place early in 1942 in which reports of unknown object/s over Los Angeles triggered a massive anti-aircraft artillery barrage. Initially the target of the barrage was thought to be an attacking force from Japan, but it was later suggested to be a lost weather balloon or a UFO. The true nature of the object/s remains unknown.
I've read and listened many different things on this subject and I've come to the conclusion that there was something going on with this entire matter. Quoting: Question EVERYTHING 333112
What I find interesting is how right after WWII was when we started seeing the first UFO's over America. I've watched enough video now to have a pretty good idea that the Nazi's were messing around with anti-gravitational devices where mercury was placed in some sort of container and vibrated to very high frequencies using electricity. It sounds rather far fetched but it's pretty coincidental to see how right after WWII our space and defense forces and craft seemed to take a huge leap forward in progress.