We apologize in advance for the length of this document. We didn’t have time to edit it down — Ed.
Part III: Types of Caches
Imagine a graph with two scales. Those scales are labeled Security (call that the X Axis) and Convenience (Y Axis; sometimes called Accessibility, but Convenience is rather more than that). A scatterplot of every cache you have made, will make, or might make would, we argue, describe a linear function: the more secure it is the more a pain in the neck it is to access.
A cache can be as simple as an old H&R Topper and a box of shotshells left in a disused outbuilding, or it can be a vacuum-sealed concrete sarcophagus at the bottom of a body of water, that requires a workboat with a crane, flotation devices, and a team of divers to recover.
Emplacement, removal, or maintenance of caches can all be summed up as servicing. Caches are most commonly exposed in-place by ordinary activities of normal people; when adverse parties compromise a cache, it’s usually during servicing activities.
Yet, a cache that has not been periodically serviced, at least inspected, is a cache that cannot be counted on.
A cache’s security is inversely proportional to the exponential number of people aware of it, just as its convenience is directly proportional to that number. Cache locations can be passed on by the emplacer(s) showing the new initate the location, or by the emplacers writing a cache report. Every clandestine organization we are aware of has required written reports; both the report and the show-me method of pass-on have different, non-zero risks. After all, “three can keep a secret — if two are dead.” Once the report is written, security of the report and its location becomes a concern. A filing cabinet full of cache reports, fallen into enemy hands, can leave entire insurgencies unarmed and most definitely afraid.
With these principles in mind, there are several types of caches. These include:
- Covert Concealment
- Clandestine Concealment
- Burial, and
Covert (usually Outdoor/Outbuilding) Concealment Caches
These are the easiest caches to find and recover, but they’re also not very secure against accidental discovery. These items are more truly hidden than cached. SF doctrine advises only to use such a cache when it is unusually secure, or is a cache of “ready items” that must be accessed in a hurry, like a small underground combat element’s non-concealable arms. Best used for temporary purposes.
Clandestine Concealment Caches
This subset of concealment caches is the equivalent of your typical spy cache: it is meant to survive careful searches and contain extremely incriminating materials. If you have seen the movie, The Lives of Others, the playwright conceals his unregistered typewriter in such a cache (which is exposed during a search because its location has been betrayed — an important lesson about cache security in general: it is only as good as your personnel security). Such a cache tends to be slow and difficult to access, and to contain relatively small quantities.
A crude clandestine concealment cache is frankly worse than just throwing the cache material in a drawer under the baby blankets. Things like the British faux-furniture gun cabinets shown above would likely give up their secrets in a two-bit burglary, let alone a professional search. The more readily (and thoroughly) integrated products from Tactical Walls might be a better choice, if you haven’t got the carpentry to build what’s in the Secret Hiding Places book in the References below.
This is the most common type of cache in the real world. Buried caches are quite secure while cached, but servicing such a cache is time-consuming, noisy, and risky. They’re also easily lost, as is illustrated by the scores of forgotten World War-era caches that European construction projects have dug up. Likewise, the American Venona code-breaking project was able to support the recovery of several 1930s-vintage caches emplaced by Soviet spies, that the spies that replaced them failed to recover (after the initial cohort was recalled to Moscow and shot); other caches went unrecovered by Soviet and American spies alike, and still presumably rest in parks and forests in the National Capital Area, or were buried under new construction.
Unless the cache report is extremely clear, a buried cache is quite difficult to locate, recognize, and recover. For example, Soviet-era cache reports for numerous sabotage caches emplaced in the West were recovered as part of the famous Mitrokhin Archive. But despite having manual copies of the original caches to work from, none of seven large caches identified in the USA could be recovered. This is a matter of some concern, as the caches are reported to be booy-trapped, and caches recovered from the same KGB sleeper/in-case-of-war sabotage program in other countries (such as Switzerland and Canada) have indeed been. Given what we’ve said about caches already, American counterspies worry about some kids coming across one of these caches and … FOOM. (One of the previous blown caches had 400 lb. of dynamite in it, and the dynamite was sweating. Not good).
We can’t fault the KGB (and GRU, which had a separate program) for preparing the caches. This was a responsible preparation for the eventuality that the cold war would go hot, and that’s what spy agencies do. And ours did likewise, but we did recover our caches when the Cold War ended.
Of course, it’s possible that the public story about the missing caches is just that, and they’re still in place — with eyes on them, against the day the KGB’s successors try to use them. Probably not, but hang around with CI guys for a while and you start thinking like this.
Finally, a buried cache is by definition underground: your stuff better be packed in an airtight, sealed, waterproof, bacteria-proof, grunge-proof container, or it’s going to wind up unusable. How unusable? Well, consider the famous Tulsa, Oklahoma 1957 time capsule Plymouth Belvedere: a zero-mileage car that emerged from its cache destroyed by rust and floodwaters (left).
This is the Meisterstück of cache emplacement and recovery. It is the hardest, riskiest, most challenging, and it needs the most preparation. It’s insanely secure, that’s its strong point. But what did we say about security? Right, it has an inverse relationship with accessibility, with convenience. It is such a difficult form of cache that most of the use cases we can come up with it are for small and temporary caches. The SF manual suggests it’s a practical way to deliver supplies over-the-beach to clandestinely-supported elements, and that has been done in Southeast Asia, in the Baltic States, and in Cuba over the years. This use of subsurface transfer caches puts most of the risk of exposure on the receiving rather than sending element. Once the caches are dropped off, the friendly frogmen or submarine will not be returning to the cache site — it might as well be radioactive, as far as they are concerned.
Soviet GRU frogmen used submersed caches in association with live training missions onto NATO territory in the 1980s. These were generally small, temporary, mission-support caches only, to the extent that we in the West understand them.
Part IV: Cache Best Practices
Let’s start with a story, before we go laying down rules. A story from Northern Ireland, via the US Armys Combined Arms Lessons Learned (CALL) Center:
During the early years of the Irish Republican Army’s (IRA’s) campaign in Northern Ireland in the 1970s, a Royal Engineer officer, Captain Winthrop, created a list of key analytical features to help find IRA weapons caches.10 It turned out that focusing on these features greatly increased the chances of finding caches. The list included the following:
● The IRA quartermaster (responsible for weapons supply) would build the weapons cache in a place that allowed friendly observation at all times. Early in the conflict, a quartermaster would often place the cache in line of sight of his own house.
You might be able to figure out why they outgrew that practice.
● The cache could be evacuated out of direct line of sight of a surveillance asset.
● The location was marked by some easily recognized feature (lone tree, specified telephone pole, derelict house) and then by some small local mark on that feature (a scratch on a tree or a stone). This micro-terrain enabled outsiders to collect the weapons by following instructions.
Key to all clandestine location-based activities, including caches, dead drops, and personal meets: recognizability, and some way to pass it on.
● The cache location had several routes of access.
And multiple paths of egress. Very important if you’re servicing your cache and PC Plod appears athwart the path you took in, calling on you to give up in the name of The Law.
● The cache itself was usually a metal milk can, sometimes buried under or inside a stone wall, where signs of disturbance could be easily disguised to avoid detection.
Using our framework, the reader can see that the first, second, and fifth items fall under the area of security: the IRA wanted to ensure that the site was watched at all times, but was in a location where it could be evacuated outside of anyone’s line of sight. The third item indicates that they used the micro-terrain to advantage for accessibility. Further, they used multiple ingress and egress routes for the cache, the fourth item to affect both accessibility and distribution.
Naturally, that whole document is worth the read, as there are many other case studies and some best practices in there.
Here is a rough, ready (and honestly, incomplete) list of caching best practices:
- Understand your user(s). A cache gets more complicated the more people (and the more diverse the people) that need to get at it. A cache only one person needs is the simplest.
- Understand your threat. For instance, if you were the Iraqi insurgents who hid their guns in mud walls, you probably had a serious case of Resting Bitch Face when the coalition started using metal detectors and ground-penetrating radar to find them — about a week later.
- Plan before you build.
- Don’t over-plan; execute the cache.
- Practice caches are a great way to polish your skills. So is putting multiple secret compartments in your house, even if you never use them.
- In-home caches have a key weakness: what if you can’t get to your home? (If you are suspected, it’s probably under surveillance. These days, by a small camera you can’t spot, not a goon in a trenchcoat out of cinema noir).
- Indeed, a cache site should not be in your, or an underground member’s, home. It should be in a neutral place (unless you can place it in such a way that its exposure compromises a collaborator) and it should not be in a place that the auxiliary or underground is using for any other purpose. The compromise of one use will expose the other!
- Always have cover for status (who you are) and cover for action (what you are doing) that adequately explains why you are going where the cache is, doing what you’re doing, and having whatever you have. If you’re in a churchyard at 0300 with a shovel, you’d better have a real good story. (If you’re standing open a grave full of rifle crates, it won’t matter how good your story is).
- Surveil the cache for 24 hours before attempting servicing. Have cover to the extent possible for this surveillance (surveillance is its own, extremely deep, topic).
- Homemade concealment caches (for example, your own variation on the dog food can as described in The Construction of Secret Hiding Places are 100% better than store-bought “hide-it” gimmicks. Everybody who’s ever going to search your stuff has seen all of those gadgets in training, seriously. If you bought it from Brookstone or SkyMall (before SkyMall went tango uniform), you might as well mail your cache report to Official Villain in care of Adverse Party Counterintelligence Agency. Remember to include enough postage!
- Things may stay in your cache longer than you think, like these 1950s Egyptian “Port Said” copies of the Swedish M45B submachine gun. The cache was carefully emplaced, probably during the 1956 Arab-Israeli war or subsequent Fedayeen actions, but never retrieved, until Israeli archaeologists stumbled into them. The emplacer thought he took care by oiling the guns and ammo, and sealing them in a truck inner tube but… well, you can see (story here in Hebrew).
- If you have something serious to hide, provide a plausible distractor cache. The criminal example is having a cache for your murder weapon that’s behind the cache for your weed. Officer Friendly usually stops at the weed. Counterinsurgency troops probably won’t be nearly as alarmed to find, say, a cache of stolen antiquities than they would be to find the half-ton of Semtex you planted the antiquities to lead them away from.
- It’s preferable to prepare and package the cache contents off-site. This reduces time on the site and risk of exposure. However, it may make transport of the contents even more risky than it already is. (Again, Access wars with Security).
References and Documents
McAfee, James. Best Practices in Counter Improvised Explosive Device Environments. 2010-03 Urgent Enemy Tactics, Techniques, and Procedures (UETTP) (Fort Leavenworth, KS: CAC/CALL, March 2010)
Robinson, Charles (pseud). The Construction of Secret Hiding Places. El Dorado, AR: Delta Press, 1981. Available as a pdf scan from: http://ready4itall.org/wp-content/uploads/2013/05/Secret-Hiding-Places.pdf
Shakarian, Paulo, and Otstott, Charles P.. What is Old is New: Countering IEDs by Disrupting the Weapons Supply. Military Review July-August 201. Retrieved from: http://usacac.army.mil/CAC2/MilitaryReview/Archives/English/MilitaryReview_20110831_art009.pdf
Uncredited. Found: weapons cache hidden days after Dunblane massacre. The Telegraph. 13 March 2013. retrieved from: http://www.telegraph.co.uk/news/uknews/law-and-order/9821627/Found-weapons-cache-hidden-days-after-Dunblane-massacre.html
Uncredited. ST 31-205, U.S. Army Special Forces Caching Techniques. Fort Bragg, NC: JFK Special Warfare Center.December, 1982
Uncredited. Special Forces Caching Techniques. (This is an edited and cut version of the above 12/82 ST, reprinted by Delta Press). Available as a pdf scan from: http://ready4itall.org/wp-content/uploads/2013/05/SF-Caching-Techniques.pdf
Uncredited. TC 31-29/A US. Army Special Forces Caching Techniques. Fort Bragg, NC: JFK Special Warfare. This is a much bowdlerized version of the now-classified TC which was developed from 31-205. It has better illustrations than the 1982 version but is otherwise inferior. Text of the document (no illustrations) available here: https://archive.org/details/milmanual-tc-31-29-special-forces—caching-techniques