Via Commander Salamander, I found this chart vaguely disturbing, yet not as troubling as I first thought. It turns out that the United States Navy currently has 283 warships in commission -- the lowest number since just before we entered World War I. Or, as Salamander puts it, "the age of coal."

On the one hand, that's a frightening thought. We have security concerns and commitments all over the globe, in all the seven seas, and that's a very, very small number to meet all our challenges. And I think it's a fairly safe prediction to say that the Navy will not expand during the Obama administration.

On the other, though, the sheer power represented by those relatively few vessels is tremendous. A single American battle group could easily defeat the entire navy of any other nation on earth.

Further, other nations have drawn down their navies, as well. We don't have an active "enemy" right now, and haven't for about 20 years. The closest thing to an active threat is the Chinese navy, and they're still several years from posing a major threat. The same with the Russians -- Putin's rattling his saber, but the former Red Navy is a pale ghost of its peak. I read that if you added up all the tonnage of all the warships in service today, over half of it would be attached to the Stars And Stripes.

But fleet-on-fleet combat is but one of the challenges our Navy faces. For example, piracy is resurging. We all know about the Somali pirates, but that's not the only place. Look at this map of reported pirate attacks just from this year.

Piracy ain't Johnny Depp. Piracy is the original "terrorism." Piracy was one of the first challenges of the United States Navy, and fighting pirates is one of the prime duties of every warship of every nation. The global decline in navies has created an opportunity for piracy to return -- and it is doing so.

Purely on the basis of power, and destructive potential, I'd argue that our Navy is more powerful today than it has ever been. (With the possible exception of the late 1980's.) But that power is concentrated in fewer and fewer hulls, and that means that less and less ocean is covered at any time.

"Nature abhors a vacuum." While it might not quite be true in physics, it's certainly true in politics. And right now, there is a vacuum in power at sea.

We all should worry about what will seek to fill that vacuum.