There are many things it could be but to me what it is isn't really very important. I am surprised the Navy admitted it especially now when all the whacks are gathering around Roswell and some even still seem to be talking about storming Area 51. This would seem to give them some additional motive to try and storm the place which is no doubt very ill advised and likely one of the biggest mistakes most them will ever make.
I think it was all just a matter of timing and popular perception.
For instance, the US just pulled out of the medium range ballistic missile treaty with Russia. Two weeks later, they reveal that they have a workable medium range missile. They obviously had been working on it for some time, but couldn't get caught doing it because of all the bad press that it would bring. But Russia (and China and who knows who else) was pushing ahead with theirs, playing the semantics game. The US was constantly being slammed for not being prepared and falling behind our adversaries - but now those gripes have disappeared.
I think a similar thing is happening with anti-missile missiles and hypersonic weapons. They military industrial complex is always working on new weapons - with taxpayer dollars. And with most they allow the conspiracy theories to circulate and say nothing - sometimes for years - claiming "national security". Only when it's convenient do they reveal things. It's all about the timing.
