I can't think of any. However, the government can keep a secret reasonably well if it so desires. Stealth aircraft tech was a well kept secret until the DOD finally released the first public images of the F-117. Of all the hypothetical concepts floating around at that time. None that I can recall bore resemblance to the F-117 that finally emerged. Once most experts saw the F-117, they commented on a plane that looked like it shouldn't even fly.<br /><br />By the same token, the fact that there were even hypothetical concepts and public discussion about stealth shows even that secret was not totally kept.<br /><br />Conspiracy proponents will tell you that even the UFO coverup is not a well kept secret because many folks connected to all the going ons have come forward. Only problem is, they almost always come forward with unverifiable evidence or info.<br /><br />Therefore, I always look at it like this...its possible there is a conspiracy within government regarding the coverup of ET visitation...but based on the evidence I have seen so far, including that which you mentioned...I'm not convinced. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>