When you belong to the military of a wealthy nation state, there are many options to solve problems. Green Berets are taught to fight on the cheap, using what is available locally. This makes things a lot more interesting.

There is a story I like to tell about a repair man that embodies the mindset and skill of a Green Beret. One day, the big office remote printer broke down, and a repair service was called in. Thirty minutes later, a guy with a bow tie and a briefcase full of tools shows up. He turns on the machine, checks the settings, and makes a few measurements with a ruler. He then pulls out a small hammer and wacks the side of the printer.

Immediately, it whirs to life and starts spitting out pages. As the office manager stares in slack-jawed amazement, the repair guy writes out a bill for $500.50 and hands it to him. The manager says, “Hey, wait just a minute. How can you charge me $500 when all you did was walk in and hit my printer with a hammer?” The repairman smiles and says, “I only charged you 50 cents for the hammer strike; the $500 was for knowing where to hit it.” Green Berets know where to hit, and in this article, I am going to tell you how they do it.

Trained to operate in denied areas, Green Berets are forced to conserve resources. After watching 14 years of video where guided weapons fall from the sky to blow up terrorists, it is natural to assume that the hammer is our primary tool and every problem is a nail. In a denied area, U.S. air support may not be an option due to time constraints (a fleeting target vulnerable in a short time window), political considerations (if we want to be friends, we aren’t going to openly drop bombs in your country), or deniability (maybe we want to tie the victim to a false source of the attack). While dropping a JDAM or unleashing a Ranger battalion certainly makes a point, it is not always our best move.

A well-crafted piece of sabotage can be more effective than a bomb. This happens a lot more than you think. I am not going to tell any war stories involving classified situations, but there is some outstanding work in the field that I can talk about. A recent example of this is STUXNET. Worried about the Iranian nuclear program, somebody (almost certainly a group of national intelligence services) wrote a computer program, put it on a USB drive, and got it inserted into the computer that ran Iran’s Natanz nuclear fuel-refinement facility. It is believed to have destroyed up to 1000 centrifuges between November 2009 and late January 2010. No commandos, no bombs, a lot of intelligence, and a little analysis delayed the creation of a nuclear weapon for five years and counting. To this day, no one knows for sure where it came from.

So how did the designers of STUXNET figure out what to do? CARVER told them. Sabotage plays a key role in unconventional warfare. The acronym “CARVER” was designed to help Green Berets destroy selected target systems in support of national objectives by identifying vulnerable nodes within critical infrastructure. CARVER is an acronym that stands for Criticality, Accessibility, Recuperability, Vulnerability, Effect and Recognizability.  CARVER is used to identify and rank specific characteristics so offensive resources can be allocated efficiently.

I can assure you that there was a top to bottom CARVER assessment of the entire Iranian nuclear program.   There were certainly multipile vulnerabilities discovered and attacked.  One of these identified vulnerabilities was the centrifuge facility (vital to enriching uranium to weapons grade).  Within that node, the central computer control system was identified as critical, a method was found to access it, it was slow to recuperate and vulnerable to computer virus who’s effect would not impact civilians. The most sophisticated part of the virus was the recognizably component. It was loaded on thousands of machines, but did not activate until it found the one specifically targeted facility in the world.

The origin of the CARVER matrix  is shrouded in mystery from the very dawn of Special Forces. Some say the OSS developed it during World War Two, some say it was the first Green Berets in the ’50s. Over the years, there have been minor refinements, but applying CARVER is a basic SF skill.

The CARVER selection factors assist in selecting the best targets or components to attack. As the factors are considered, they are given a numerical value. This value represents the desirability of attacking the target. The values are then placed in a decision matrix. After CARVER values for each target or component are assigned, the sum of the values indicate the highest-value target or component to be attacked within the limits of the statement of requirements and commander’s intent.”—U.S. Army Field Manual 34-36

CARVER analysis is summarized in a six-column, five-row matrix. For each target, a rating of 1-5 is given for each column. A ‘5’ rating meant it favored the saboteur, whereas a ‘1’ meant it favored the target. The best score for the saboteur was 30 (6 x 5), the worst being a 6 (6 x 1).


The ratings in CARVER are very subjective. While the concept is simple, a deep understanding of the target and available resources to attack are vital to producing useful output. It is best done by the entire SFODA.

CARVER is the most stolen and misused idea ever conceived by Green Berets. The Internet can tell you how to use CARVER for everything from picking up girls to writing a grocery list. There are a number of classified programs where SFODA’s are tasked with performing security vulnerability assessments of sensitive facilities and programs using CARVER. This has spawned a security industry selling computer programs and analysts to do…CARVER.

I don’t know any recent unclassified CARVER stories, so I would like to give a great historical example. During World War II, the Allies were very concerned that the Germans would develop nuclear weapons (just like Iran today). An analysis of the German program revealed that the production of heavy water for use as a moderator was critical to the program. The Norsk hydroelectric plant in Norway produced heavy water as a byproduct of fertilizer production. It was the only source in the greater Reich capable of producing heavy water in useful quantities. Norsk Hydro was the critical node. It was complicated and vulnerable. If it was put out of action, it would take years to rebuild, thus it was considered non-recuperable. The loss for the nuclear program would be catastrophic. The plant was easily recognizable.

While Green Berets made up CARVER, they did not invent target analysis. That distinction belongs to the proto-humanoid who figured out how to pack-hunt the woolly mammoth, but that is another story. The British Special Operations Executive were professionals. They identified the vulnerability of the Nazi nuclear program. A CARVER-like analysis of the plant itself revealed that a few small explosives charges in the right spots would halt heavy water production.

That left only one problem: accessibility, but that was a mother. The plant was on the side of a mountain surrounded by a civilian populace of a friendly, though occupied, allied nation. Let’s send in commandos!

Operation Freshman was conducted by glider-borne British engineer paratroopers. The first glider crash landed after the tow rope snapped. The second glider and tow plane flew into a mountain. Most of the aircrew and a number of airborne troops were killed on impact. Those who survived were taken prisoner and executed in accordance with Hitler’s Commando Order. Realizing the vulnerability of the plant, the Germans added mines, floodlights, and additional guards.

The only good thing to come out of this was the British Special Operations Executive (SOE) had successfully placed four Norwegian nationals as an advance team in the region of the Hardanger Plateau above the plant. It was now time for plan B. Six more SOE agents were dropped in.

A Norwegian agent within the plant supplied detailed plans and schedule information the SOE team used to plan their infiltration and attack. Avoiding the one heavily guarded bridge, they walked through a ravine, crossed the icy river, and climbed the steep hill to the plant. They then followed a single railway track straight into the plant area without encountering any guards. They entered the basement through a cable tunnel and a window. They ran into a Norwegian caretaker who was happy to help out.

The SOE team placed explosives on the electrolysis chambers, and attached time fuses. After a brief delay to find the caretaker’s glasses, the team activated the timers and walked out smiling. The charges destroyed the electrolysis chambers. The entire inventory of heavy water produced during the German occupation was destroyed with equipment critical to producing more. The team avoided the 3,000 German soldiers searching for them. Five of them skied 250 miles to Sweden, two went to Oslo, and four stuck around to work with the resistance.

CARVER is an example of teaching Green Berets how to think, not what to think. It is a framework to organize your thoughts to plan a mission. It is a tool only useful to the creative and intelligent mind, but properly employed, it can change the fate of nations or pick up girls. Think like a Green Beret, but use your powers for good.

(Featured image courtesy of businessinsider.com)