What's Our Most Misunderstood Secret Military Project?

We, as humans, have a tendency to get a little speculative when it comes to the secret goings-on of our militaries.

Take, for instance, Area 51. It's a base that has secret military jets and shit. Naturally, people got it into their heads that is was filled with aliens. I mean, it certainly seems like there's secret stuff going on over there, just not extra terrestrials.

What other secret military projects, past or present, American or otherwise, have been massively misconstrued by the imaginative public?

Photo Credit: Lockheed