Black triangular-shaped UFO spotted in Argentina

On December 2, 2015, an inhabitant of Cabot (in Argentina) was taking a dog outside when he has seen an impressive black triangular-shaped UFO in sky. According to him, it could be a secret military airplane…

Witness statement:

I was taking a dog outside when I noticed an owl flying from a tree in my side yard. I pushed the dog into the backyard and went back to see if I could see the owl again. That's when I spotted the triangle. It seemed to be completely matte black, and had no lights on it. I wouldn't have been able to see it had it not been low enough to the ground for the street lights to slightly illuminate it.

When I first spotted it, it was parallel to the ground with one point in the direction it was traveling. I'll call this the nose. The nose seemed to be slowly pitching down though it's altitude and path did not change. To me, it seemed like gravity had no hold on it, and it did not appear to be powered up (but what do I know about these things?). It moved slowly, maybe highway speeds, but almost certainly under 100mph, though its difficult to judge without knowing exactly how big or far away it was.

It seemed to be mostly flat with some detail on it. The object was a solid equilateral triangle with a height roughly 15-20% that of one of its sides. The tail edge was broken up in a manner similar to the picture I've attached. Sorry for using a "classic" TR-3B image, but what I saw really did look like what you get when you plug tr3b into google. However, in regards to the attached image, what I saw did not have a pyramid shape, the tips were more rounded, and it appeared to have "greebles" (for lack of a better word) on the surface. As far as its size is concerned, it was larger than a Cessna, but much smaller than the C-130s that fly around this area.

As far as the other bullet points listed:
3: I thought (and still do think) it was probably some top secret military air/space craft.

5: Survival instinct triggered my fear response at first. Never seen anything like it, but that quickly dissipated into pure elation and joy. I've been looking at the skies for years trying to spot something I couldn't immediately explain, and there it finally was. The whole event lasted a matter of seconds. I could have hit it with a green laser pointer, but that probably wasn't a good idea. It might have a bigger laser, after all. My pocket flashlight was too small to reach it, and neither my cell phone nor my DSLR would have been able to focus or pick up enough light to get anything. Which brings me to...

6: I lost it behind some neighborhood trees. Like I said, it was low and I only spotted it because of a clearing where the neighbor's house is.

In closing, I got the distinct feeling this was a man made object. I really have nothing to base that on, except nothing about it screamed "alien" to me. Maybe I've been jaded by years of sci-fi movies and TV.