You mean you think there's a classified fiber network operated by the government that covers the entire country and transports about as much data as the real internet?

So, are those cables marked on maps or with signs (like legit cables are)? Or can any idiot with a backhoe cripple this secret network at any time? It seems that a secret network would have much much lower operational reliability because of how many idiots we let drive backhoes in this country.

Dude, my brother works in excavation. Not cool.

Seriously, have you not heard of dark fiber? It's quite common for a network owner not to "light" many of the fibers in a particular run. Sometimes, this is because the capacity is not needed, but it's also common that the network owner's customers prefer to run their own multiplexers. Those customers could include the NSA or whatever agency in the government. Many such agencies certainly have built multiple classified networks this way.

Your average backhoe operator doesn't know what's in the pipe any more than the Dig-Rite spraypaint guy or even AT&T technicians do. The sign just says, "Buried Cable: Call Before Digging". Of course sometimes cables get cut anyway. That's why excavators get bonded. That's also why networks that aren't designed by "idiots" are redundant.

Sorry, no offense meant to professionals. I was thinking more of random guys who rent a backhoe for the weekend.

And yes, I know about dark fiber. Dark fiber networks don't have traffic but they're still on maps and have warning signs around them. There's a difference between burying fiber without using it and keeping the existence of fiber totally secret.

I guess I don't see how we could have a parallel internet whose existence was unclassified that no one noticed until now.

Well, I guess it depends on your definition. When I worked in telcom we called it "dark fiber" if the multiplexers at each end were operated by someone other than the owner of the fiber. This was "dark" in that the network owner didn't know anything about it besides who had access to the server closet in the CO.

The point is that the USA government leases a great deal of network capacity, both directly and indirectly through "cover" entities. Much of that is probably used to build any number of networks that carry "classified" data, including SIPRNet, NSANet, JWICS, and others so "dark" that we don't technically know they exist. Nobody would bother to deny the existence of these, nor the obvious fact that the actual fiber belongs to the same firms that own all other long-distance fiber: ATT, L3, XO, VZN, etc.

I suppose it's possible that some agencies operate the sort of "secret network" you were challenging, but since it costs at least ten times normal prices for spooks to do anything, they probably try to keep that self-built stuff to a minimum.

EDIT: Just so we're clear, the security of a network does not depend on no one knowing it exists or where it is. The NSA knows encryption: no one is going to "tap" their fiber and find out their deep dark secrets. A well-informed goat enthusiast with a backhoe could conduct a denial-of-service attack, but that doesn't scale and as I said these networks have redundancy built in.