The M18A1 Claymore Mine – A “Persistent” Mine

The United States government published its current landmine policy in 2004.  Some of the key items in the policy include plans to “eliminate all persistent landmines from its arsenal,” “not use any persistent landmines — neither anti-personnel nor anti-vehicle — anywhere after 2010,” and “develop non-persistent (self-destructing/self-deactivating) landmines” (State Department).  The US issued this policy in lieu of signing the Mine Ban Treaty and while the landmine policy is under review by the Obama Administration, the speed of that review and recent procurements suggest that there will be no immediate changes.  Instead, the US Army, while developing the Spider Networked Munition System (see previous post), is also buying a lot of newly-made M18A1 “Claymore” anti-personnel mines, mines that do not have self-destructing or self-deactivating features in the current model.

On February 14, 2011, the US Army issued a Request for Proposals for companies to make up to 255,000 M18A1 Claymore mines for delivery to the Army through April 30, 2016 (FedBizOpps, Solicitation # W52P1J09R0088).  The total value of the contract, ultimately issued to Spectra Technologies, LLC of Camden, Arkansas on June 23, 2011, is up to $100 million over five years (FedBizOpps, Award # W52P1J11D0077). The problem with Claymore mines is the fact that they may violate the Mine Ban Treaty and the intent of the US landmine policy is to put the United States in compliance with most of the Mine Ban Treaty’s provisions without actually acceding to the treaty.

The size, shape and usage of Claymore mines are very distinctive.  Claymores are directional, fragmentation mines that use a small amount of explosive to propel 400 to 700 steel balls across a 60 degree arc and an “effective” range of 50 meters.  US models have the words “Front, Toward Enemy” helpfully stenciled on one side so you know which way the steel balls will go.  Claymores are meant to be used against people, not vehicles and referred to by the Army and others as “anti-personnel mines” (; FedBizOpps, Solicitation # W52P1J-09-R-0088; FAS).  Because of the effectiveness of Claymore mines as anti-personnel devices, many armies, including the Chinese, Russian and Swiss, have produced their own variations. 

M18A1 Claymore Mine, Photo Courtesy of WikiMedia

Claymore mines historically have had two modes: a command-activated mode and a victim-activated mode.  In the command-activated mode, the soldier who has set up the mine will activate the mine using an electric detonator switch.  In the victim-activated mode, the mine is set up with a trip-wire that activates the mine when the trip wire is broken.  Not being a government contractor, I could not access the most recent Technical Data Packages for Claymore mine specifications (as part of solicitation # W52P1J-09-R-0088), but the basics of the weapon remain the same in the solicitation descriptions.  The most recent description from the US Army office responsible for munitions describes Claymores as “detonated using an electric or non-electric initiation system and is used to deter enemy pursuit, establish perimeter defenses and conduct ambushes” (PMCSS).  In the absence of an explicit mention that Claymores can no longer be activated via tripwires, I am willing to assume that tripwire-activation remains a possibility.

It’s the victim-activated, trip-wire function that makes the Claymore mines controversial.  According to the International Campaign to Ban Landmines, Claymore mines that are used solely in the command-activated mode are permitted under the Mine Ban Treaty.  In 2003, only Sweden – among all States Parties to the Mine Ban Treaty, twenty of whom had reported stockpiling Claymores – had taken steps to modify its stock of Claymore mines to ensure they only operated in a command-activated mode (ICBL, pdf).  By 2007, thirty States Parties had reported stockpiling Claymores, but only six – Belarus, Denmark, Lithuania, Moldova, New Zealand and Sweden – had modified their mines to prevent victim activation.  These States Parties chose “to physically modify the mine to accept only electric detonation and some have physically removed and destroyed the tripwire assembly and appropriate blasting cap.”  Some states, including Bosnia-Herzegovina and Germany simply destroyed all of their Claymore stockpiles rather than make the Treaty-mandated modifications (ICBL, Word Document; ICBL). In 2010, ICBL reminded the States Parties in attendance of the Intersessional Meetings in Geneva “to report on the destruction of sensitive fuzes and on steps taken to ensure that Claymore… Mines can only be used in Command-Detonated mode” (ICBL, pdf).

The United States granted an exemption for command-activated Claymore mines in the export ban on landmines in 1992, however, the statements by ICBL and the fact that the model number for Claymores has not changed in many years, suggests that the M18A1 Claymore retains its victim-activated properties. Until the Claymore is completed eliminated or substantially modified to remove the “non-electric initiation system,” a fantastic euphemism for “trip-wire,” then the US can never be fully compliant with its own policies and has just ordered another quarter-million violations. 

Michael P. Moore, January 18, 2012


UPDATE, February 14, 2012:

Update to posting on Claymore Mines, courtesy of Mark Hiznay, Human Rights Watch:


“The description from the Sources Sought notification, which is part of the solicitation [Landmines in Africa] cites:

‘The M18A1 consists of the M18A1 Anti Personnel Weapon Body and a non-electrical initiation system packed for field use in an M7 Bandoleer. The M18A1 Anti Personnel Weapon Body consists of a molded plastic case which is lined with a single layer of 700 steel balls in a resin matrix along the inside of the convex side. The remainder of the case is filled with Composition C4 high explosive. Two folding scissor-type steel legs are affixed to the bottom edge. Molded along the top edge are an aiming site and two cap wells that accept plastic combination shipping plug / blasting cap holders. The non-electric initiation system is composed of approximately 100 ft shock-tube, Blasting cap and In-line initiation system.’

Seems [Landmines in Africa] did not understand the significant of the last sentence (Ed. Note: Mr. Hiznay is absolutely correct, I did not). What is “shock tube”, or more specifically a “shock tube detonator”?

[Mr. Hiznay lets] Wikipedia explain:

‘Shock tube detonator is a non-electric explosive fuze or initiator in the form of small-diameter hollow plastic tubing used to transport an initiating signal to an explosive charge by means of a percussive wave traveling the length of the tube.’

When did the transition for Claymore initiation in the US?

Look no further than the Landmine Monitor Report 2005:

‘In February 2004, the Pentagon requested $20.2 million to produce 40,000 M18A1E1 Claymore mines. Mohawk Electrical Systems, Inc, in Milford, Delaware is scheduled to produce the munitions between June 2005 and March 2006. The M18A1E1 will incorporate a new triggering system that does not rely on either the victim-activated mechanical tripwire fuze or the command-detonated electrical initiation provided with the M18A1. Instead, the Claymores will be command detonated by a new generation of modernized initiators that use explosives to trigger the mine.’

The M18A1E1 is the developmental designator for the modified M18A1, in practices it’s the same munition. Bottom line: there is no conspiracy in the term “non-electrical initiation system” – it’s a pyrotechnic system now, still command detonated.

Additionally, a member of the US military would be violating US policy and DoD Directive, and thus subject to sanction, if they use a Claymore with a tripwire, which is recognized by the Bush Policy [the 2004 US Landmine Policy] as an antipersonnel mine. Remember, the use of Claymores with tripwires authorized was only valid until 2010 and only in Korea.”

Thank you, Mark, for the clarification and explanation.  If you ever have any additional comments on what you see here, feel free to post.


Michael P. Moore, February 14, 2012.

5 Comments on “The M18A1 Claymore Mine – A “Persistent” Mine”

  1. Patrick says:

    Sir, I have just read your article in reference to ‘Persistent Mines‘.

    Has no one there ever heard of the non-ComDet (command detonated) (but still) electrical method of trip wiring the Claymore?

    This method is known to every true grunt that was in Vietnam, but I have never seen it show up in an Army FM nor any other ’Trade Journal or Magazine’ dedicated to the taking of human life.

    I will be purposefully vague about the details of this method for obvious reasons. No reason to give the kiddies new (or rather old) ideas.

    It simply involved using a battery(s) (BA 30>flashlight or low PRC 77>radio) for the power source and the supplied M-18 accessories with some minor modifications such as cutting off the plug for the detonator box/firing trigger (affectionately known as the CLACKER), then separating the two wires and stripping back the insulation an inch or so and securing them to the electrical source.

    The ‘circuit’ is also interrupted closer to the Claymore and using two C-Ration spoons taped together (outside bottom to outside bottom) and with the wires run through it in the aforementioned vague manner and a small (2”X2“) piece of poncho, or other non-conductive material, a crude but effective switch is made. The tripwire is tied to the piece of poncho through a small hole, the piece of poncho is inserted between the two spoons, and when the target hit’s the tripwire it pulls the poncho from between the two spoons, closing the circuit and initiating the Claymore.

    The above method is effective for ‘daisy-chaining’ an entire kill box and commo-wire is very efficient should addition wire be needed.

    The above was not to give a lesson on the electrical method of a target detonation as opposed to a ComDet, it was to show that it can and has been done, in literally thousands of cases. An exhausted grunt will use this method for perimeter denial when there is a good possibility of sleep interfering with perimeter or O.P./L.P. guard duties. Most of these mines were picked up when the unit departed the area, however, a Claymore employed for the rear security of a moving column or element of men, attempting to break contact, could not and would not be picked up or they could not have done their job (slowing or stopping pursuit).

    All of this to say, regardless of removing the firing ports for non-electrical use, if there is an electrical port there is a method to set it as a “persistent mine“. Grunts don’t give a damn about treaties, they just want to go home in one piece. Just sayin’…

  2. Logen says:

    I think that it is terrible that there are so many mines left from the wars before, yet, as someone who was in a conscript army, mines are highly effective. Hopefully, there will be newer variants that self-deactivate after some time. This would at least somewhat alleviate the issue. I do not think militaries would be willing to ban them outright.

  3. I Corps says:

    We used old PRC 25 batteries to power Claymore mechanical ambushes. C rat spoon cut down, two stripper clips a rubber band and some trip wire, use 3-4 Claymores. Works great. I also know that in the pulse from detonation of 3 or so daisy chained together will sometimes set off claymores 50+ ft away. Me? I really like Claymores. I am sure they saved many Americans in Vietnam. None of the people who died from our Claymores in VN were “victims” they were the enemy.

    • Patrick says:

      I too, have a problem with their constant use of the term victim. If someone walks into the kill zone of an American ambush, they aren’t victims, they’re combatants. At 0200 a REAL rice farmer is at home in bed. The guy walking around out there at that time of night is either Charlie or straight up NVA.

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