USOs--Underwater Submerged Objects

I watched a fascinating documentary on the History Channel on the phenomenon known as USOs or Underwater Submerged Objects--basically deep sea UFOs. Quite creepy actually. They claim that through the years objects, underwater crafts have been spotted and perhaps lived or survived in ocean depths for years. These are believed to be alien craft . . . or something.

The difficulty with the USO phenomenon is that unlike UFOs, which everyone can see, mostly only Navy's can and do spot these USOs and so if they exist, and many believe they do, the evidence is top secret.

They gave accounts of the Argentinian Navy, the Norwegian Navy and the US Navy tracking these things. In the case of the Norwegians, the USO emerged and flew briefly and then re-submerged. They actually fired on the craft and block off the Fjord for days to trap it to no avail.

Here is Wikipedia on USOs.

I watch the History channel on occasion, especially their shows on the Universe and Gangland. I'm not sure if they are considered credible. Does the fact that the History Channel made a case for USOs give these things plausibility?

I for one am a believer in these things. In fact my novel does have Aliens submerged and concealing their activities and craft in the oceans. It makes perfect sense if they want to not be disturbed.