To me, the possibilities are:
- Terrestrial. Either our government (with the left hand not knowing what the right hand is doing), or China. Either way, I'd believe they'd have to be drones and not manned. With the technology being way out of our understanding, the medical science might be even further out. Hard to imagine a human being able to pull 700 g's when we can barely do 17. If it is say China, it also begs the question as to why they just don't take over. There have been at least two reports of these devices being able to shut down nuclear power at will. Perhaps they have limited use/access to this technology and they're afraid to lose it, no matter how superior it is.
- Non-Terrestrial. Again, the question is asked why they wouldn't just take over? But we're so primitive to them, there would be no need to. Unless they need our resources. They would be more curious than anything. Their technology is obviously way out of our league, so our limitations in space travel would not apply to them. We would have no concept of how they are doing it.
- Time travelers. A silly possibility, but who knows. As far as we know, you can only travel forward in time. But when you're going 13,000 mph and can turn on a dime, these guys might know how to break the rules.
- Aquatic civilization. The silliest and least likely explanation. There's so much of the ocean that we don't know, and these guys have been seen to submerge themselves. Maybe they come from some lost Atlantis-type of civilization that is just far more advanced than us. But they keep popping up on both sides of the ocean, and you'd figure by now we would've stumbled across something in some of the more shallow depths.
I definitely think there is something to this, and it's not just some hoax or "weather balloons" this time. It will be interesting to see what the December report will say, but I suspect it won't tell us much more than we've already heard.