I'm going to leave this for whoever is willing to read it:
I went to college with a guy whose grandfather was one of the primary scientists the helped develop the Patriot Missile. With that comes a lot of credibility when it comes to my buddy's knowledge of aerospace engineering and phenomena that they would like to exploit. He doesn't acknowledge it now, for whatever reason, but he and I had a wonderful conversation about the government's knowledge surrounding antigravity propulsion. He argued that the U.S. government has been in the know about antigravity propulsion for decades, BUT have been unwilling to release any information about their abilities because there has been no practical way of defending said antigravity technology, especially when it's implemented in a flying craft. He said that we should not expect any public news about antigravity capability until the U.S. government has a handle on portable laser weapons.
Why? you might ask? Think of what it would take to create an antigravity craft; you're basically tasked with figuring out how to create an individual gravity field around a single craft. By doing so, all gravity within that field attracts inward. And by doing so, ballistic capabilities are rendered null; you can't shoot anything ballistic away from a craft that possesses its own gravity field. The only thing that can penetrate such a field is light, hence lasers are the only defense mechanism for antigravity craft. My buddy speculated that we would not hear about the actual antigravity capability of U.S. military aircraft until they have a strong handle on portable laser weapons. Once these weapons are common place on typical, standard military planes, then and ONLY then will information about antigravity technology be released to the public. Even then, others speculate it won't happen because the situation is far too close to acknowledging the existence and visitation of extraterrestrials to Earth. The risk of that is far too great based upon diligent research by sociologists. However, I don't believe that research is any longer applicable and necessitates immediate updating. The common sociological research in this area suggests human societies would not be capable of withstanding such news that humans are not the apex predator in the universe. If anyone is interested in some good sci-fi, I recommend the "Three Body Problem" book by a Chinese author. Kind of like Contact by Carl Sagan only much more in depth.