Tiamat
I've seen the future...
The hypersonic aircraft project? Yeah, no. Hypersonic engines are stupid hard to manufacture, largely because of the sheer stresses involved...
Aliens? Not likely, largely because just trying to work out what their tech can do will get that specific scene in The Avengers where Captain America tries to fix the duct fans of the SHIELD Helicarrier...
No, the land around it is already toxic, given that they're nuclear weapon testing grounds (why Area 51 got its name, it was the 51st nuclear testing site area).
Largely because US military doctrine is predicated on the fact they've got the best aircraft...
The shape is a bit off for that... and smaller. Remember, Vulcan bombers are huge things.
Jeez, @Aaron Fox , you ruined my joke. You could have at least said "No, you impervious twit! Everyone knows there are no aliens at Site 51! They are at STONEHENGE!"
And, while being admittedly biased as ex-U.S. Air Force, it's not so much the U.S. military would suddenly collapse over having no air dominance, rather over the fact that NOT having air dominance, or at least some level of air supremacy tends to really, really suck. Hard to get troops and tanks moving anywhere, or keep your supply lines open if they're getting constantly bombed. Ask the Germans and Japanese in the last World War, or even the Vietnamese, or hell, ask the Iraqis.
CAVEAT: Though to be honest we probably tend to lean a bit more on achieving air supremacy than we care to admit. That said, I refer back to the previous point. That plus the US Army and Marine's history in regards to having effective SHORAD and AAA defense tends at best to be rather, well, mixed.