It is widely known that Alien Technology has been Backengineenered from captured Craft by the US. There are many witnesses who already came forward including former NASA Astronaut Edgar Mitchell (* 17. September 1930 in Hereford, Texas; † 4. Februar 2016 in West Palm Beach, Florida).
Quote: UFOs in the Skys all the time. But they are very likely Alien Craft, but not all of them are. I suspect some of them are home growing. I suspect that in the last sixty years or so that there has been some Back-Engineering and the creation of this type of equipment. But it is not nearly sophisticated yet as – what the appartent vistors have.
Efforts to develop Anti-Gravity propulsion systems already took place in Germany in the third Reich. They explored VORTEX technology of the UFO – and probably also TORSION technology used for Time travel. It is believed that they had functioning UFO technology at the end of the War – and even went to the Moon before anybody else did.
And it is believed that the US Navy also accidentialy steped into Space-Time-Travel during the second World War – experementing with Counter-Clockwise-Electromagnetic fields. Key is the Unified field theory developed by Albert Einstein in the late 1920s.
Technolgies to replace Oil exists for decades but beeing kept in the dark for the advantage of a few people.
The US Navy was there from the Start and probably started concpets of own Spacecraft in the early 1950s.
They probably had a operational Space fleet in the late 1980s.