Some of these secrets are indeed probably vital to the successful defense of the United States. The problem is that sometimes the way the secrets are kept are themselves kept secret, and mostly because they're exceptionally dirty. After a certain amount of time keeping secret the secret ways you keep secrets secret, a certain insanity sets in. It's an insanity of culpability; the certain knowledge that though whatever you do has the unofficial sanction of the government, were that sanction to be removed you could not only be tried for high crimes, but could be reviled as a monster by a shocked and outraged world. (Most people don't care much for the idea of medical technology in the hands of assassins; visions of the heinous atrocities of the Nazi doctors rise all too speedily in the memory.) This is, by the way, the point where espionage and counterintelligence becomes no profession, but a way of life... and in Washington, DC, this has been the way of life of the majority of the locally-raised population since they understood language well-enough to understand and follow orders. Such a way of life thrives best in the dark... it's fortunate that for the most part these people are never taught to think. Being mostly thoughtless they dread thinkers.
There's a variety of ways of keeping people stupid. One can use drugs. If you're very careful about how one will introduce a person to what will become a lifelong regimen of surreptitiously-administered control chemicals, one can do wonders with personnel management. If on the other hand, one recognizes too late that a person's intelligence is increasing, they may notice quickly when you start dosing them. This tends to lead to complications such as paranoia. In the event of paranoid symptoms, one has little recourse but to use the headcrusher machine.
There are several variants. One that I have definitely and directly seen appears to be a band of plastic, possibly vinyl or a similar strong but flexible fabric-like material. It was mounted on the end of a pole, which has a lever at the other end. Small devices which may be adaptations of surgical staplers ring the device. One person distracts the target, and the other approaches from behind and does the headcrusher thing. I've seen one version that is more like a cap, or possibly a modified military helmet. This one is ringed on the inside with some sort of devices which are also probably based on a variation of the stapler principle. One person holds it just over the victim's head, and another strikes it, hard, with a rubber hammer.
These machines are definitely intended to braindamage the victim, to do it quickly, and as near as I can tell, to primarily damage the areas concerned with memory, language and the ability to tell other people what happened.
There are also other ways of achieving the same ends. These seem to involve memory-wire, or memory-plastic (most likely). These are materials which can be deformed, and which will return to their previous shape over time. It seems that a piece of memory wire can be tightly rolled into a coil, heated to imprint the shape, and then can be forcefully straightened out and inserted beneath the scalp (or to impart a 'marking' for easy recognition) instered parallel to a long bone) where the continuous pressure will cause osteoporotic deformation. It's the exact same medical principle that orthodoncy uses. The skull slowly deforms, placing pressure on the brain within. (There's a medically-demonstrated linkage between pressure on the brain and schizophrenia. There's also a demonstrated link between brain-damage and stupidity.) I call these little implants "barbs" because they seem to be barbed at the end as are fish-hooks
Don't bother trying to get a doctor to remove the "barbs"; they've almost certainly got orders to report as a spy anyone trying to get a skullcrusher implant removed. Why else would it be there?
These devices were, I guess, originally a last-ditch resort to be used against highly-placed foreign intelligence which couldn't be displaced through normal means and couldn't be assassinated nor expelled. This simply removes their main asset, memory and intelligence. The problem is that the technology has fallen into the hands of street punks, gangsters (you'd be amazed what you can get someone to do when they've been smoking big hits of rock all night and run out of money), and other less-than-patriotic segments of the population. It might well be that about the only people who don't have it are the hoi polloi. So what we have is a city full of people running around squishing each other's heads, and the heads of anyone who they encounter whose head is not squished.
So if you come to DC and you see that people have oddly-shaped heads, and can't talk much sense, seem to have severe memory and language problems, you're probably talking to a victim of the headcrusher machine.
All that you could possibly do for such a person would be to get them out of town (hard to do), get them to a remote facility.
Expect that there will have been multiple applications of the headcrusher technology, with a few different cranial fractures. You'd be amazed how quickly people's minds return to normal once the pressure is relieved.
See also this report of implants for experimental use on criminals. If these ever fall into the hands of the people who already have the headcrusher machine, things will get totally out of control.