Well I hadn't seen the 'its an aircraft' theory. Having watched the video again though, that doesn't look much like an aircraft to me. The contrails are too thick and don't dissipate (also single engine?). It also came from 35 miles off-shore. Only an aircraft carrier is going to be able to launch an aircraft from there, and that would be the defence department's so again they would know about it.
Your second link also says
Missile tests are common off Southern California. Launches are conducted from vessels and platforms on an ocean range west of Point Mugu
Why not say so is my point? Why not just say, yep, its ours, we launched it, business as usual. It is very strange.
I'm sure more information will come to light. I just worry that the longer you wait for an explanation, the longer people have to get their stories straight.
Or maybe the US got caught with its pants down and it is indeed from a foreign nation? That wouldn't be something they could admit in a hurry. Who knows. I will wait for further emerging details.