Make no mistake: The Pentagon's got plenty of secrets you probably don't even want to know about. But there are at least a handful they likely wish had stayed a bit more covert.

Some of 'em have been talked about for years -- and new intel is still creeping out. Old documents from the CIA's MK-ULTRA program, which plied unwitting participants with mind-altering drugs, have been released as recently as last year. And the Pentagon Papers, officially declassified just this past summer, reveal disturbing details about U.S. activities during in the Vietnam War.

Try as they might, it seems top brass just can't keep every classified program entirely under wraps. And in this Internet era, it's arguable that we know more than ever about their covert activities. A combination of insider leaks, sly reporting and grainy photographs -- all distributed online -- have shed plenty of light on some of the military's biggest secrets. From stealth helicopters to undisclosed prisons, check out nine recent Pentagon programs you never should have been privy to.

It's the most covert submarine in the American arsenal. Since the sub's 2004 launch, experts have speculated that USS Jimmy Carter was designed with classified spy missions in mind. Allegedly, the sub is able to slip into enemy ports undetected and even tap into the underwater fiber-optics of foes to listen in on undersea chatter. USS Jimmy Carter may have done just that last year, when it was quietly deployed to spy on North Korea -- one of the only known missions the sub has ever taken.

What else can USS Jimmy Carter, one of the Navy's three Seawolf-class Submarines, accomplish? Nobody's quite sure, because Navy officials haven't commented on exactly what kinds of tech the seafarer is equipped with. But the Jimmy Carter does boast unprecedented hull space, to store unmanned aerial and undersea vehicles for whatever deadly missions our former president's namesake needs to embark on.