Or, our government has witnessed said technology and tried to recreate/reverse-engineer it? Makes you wonder why they would build something like this just on a without a valid reason behind doing so.
The US government seems to be quite ready to try out a lot of fringe stuff if it provides military applications (see http://en.wikipedia.org/wiki/Stargate_Project). They may as well just have gotten their inspiration from the general flying saucer hype.