I can say that it isn't aliens, because if so, everyone at roswell would be either dead, or in quarantine from alien viruses.
Is it a UFO, well no, its not in the air, but its a UGO (Unidentified grounding object) yes, I made that up, and yes, I'm proud of that name
I personally believe that either A: the goverment was telling the truth, or B: it was some drone, like a T2D2-1
It would make sense for the goverment to hide a drone, as it was a emerging technology that could be VERY useful in wartime, and if its all smashed up, who knows? it could look like a crashed ufo, although, interestingly, it uses a parachute to recover, so if the chute deploys afterwards.....