IMO the black projects have developed a lot of stuff that the regular military cannot identify. The stuff stays classified because in case of WW3 such superweapons will be deployed. The US military sees WW3 as something that must be fought and won - that is their job, so they will do it.
Beyond that though - inertial dampers and gravity nullification is stuff that may be leveraged off of alien tech. If it was developed from human "fringe science" they did a really good job of classification, compartmentalization, and ruthlessly killing off anyone who was/is a security risk.