Tripwire forces (again)

It's time to revisit the fallacy of "tripwires". I wrote about it before, but that was ages ago, nobody read it, and I really have the urge to finally deal some imaginary blow to this stupid idea of "tripwire forces" with the Force Z example.
I planned on using this example for years.

Force Z under attack
"Force Z" existed in late 1941 and consisted of the powerful battleship Prince of Wales, the elderly yet still useful battlecruiser Renown and some escorts. Aircraft carriers were not part of it when Force Z made contact with the enemy (the Japanese), but they wouldn't have helped anyway. British naval aviation was no good for anything but highly efficient nightly attacks with obsolete biplane torpedo bombers.

Prince of Wales and Repulse succumbed to the assault of less than a hundred long-range bombers when they were trying to counter the Japanese invasion of Malaya. They were both sunk within hours, on the fourth day of the Pacific War.
Prince of Wales had an extremely impressive armour scheme and both ships were fast enough to evade all but four Japanese capital ships (the Kongo class), and would probably have been able to stand their own against three of them at the same time.
The whole encounter is fascinating in many ways (even the more elderly of the two involved Japanese bomber types had the range and offensive potential to ruin Britain if it had been used by Germany in 1941/42!).

Mitsubishi G3M 'Rikko' torpedo-capable bombers.
Technically they could have de facto encircled the British islands
from bases in France and Norway if used by Germany.
Their range was phenomenal because they were designed
for maximum range with a 800 kg torpedo as payload.
Nobody in Europe had matured such a concept (the Soviets came close).

Strategically, it should have been the deathknell to the idea of tripwire forces.
These two capital ships were stationed forward at Singapore in order to deter - instead they only provided the Japanese with a good idea of how to defeat the Royal Navy piecemeal. Two capital ships of this kind were not capable of stopping the Nihon Kaigun; the best they could possibly have achieved as provoking the Japanese to assign their best battleships (Nagato and Mutsu) to the effort of invading Malaya. Eventually, three bomber groups in Indochina did the trick as well, and did so at tiny losses.

The naval theorist Mahan was concerned about the possibility that the U.S. Navy would sometime be split into a Pacific and an Atlantic Fleet and one of both might be involved in a decisive battle before the other could arrive. he already recognised the risk of splitting one's battlefleet and having it destroyed piecemeal - decades before WW2. The British did it nonetheless, as did the USN. The USN was backed by a big enough industry to effectively rebuild itself during the war. This compensated for the strategic mistake, but it didn't change that it was a big one.

Moreover, forward deployment in general should have been understood as a folly after 1941. Sadly, humans aren't that capable of learning.
NATO kept most of its Central European defensive forces East of the Rhine during the entire Cold War, for example. It was an invitation to the Warsaw Pact to overrun them, especially during one of the hundreds of really, really weird Cold War weekends (when almost all German conscripts returned home). Luckily, the Soviets never bit, as their concern was not really how to defeat the West, but how to avoid being defeated by the West.

Operation Desert Shield initially saw a lone airborne division deployed as an early  tripwire force in 1990, and those troops were fully aware they were ill-suited to deal with a couple thousand Iraqi tanks. They had only two truly effective anti-tank munitions - the TOW and the Shillelagh - in small numbers. Their Dragon and LAW munitions were next to useless against even elderly Iraqi main battle tanks and their artillery would have been very busy with other missions. Again, the potential aggressor did not bite because he wasn't really that aggressively-minded as Western public opinion had assumed based on the propaganda. As far as I can tell those fabulous satellite imagery leaving no doubts about the Iraqi intent to invade Saudi-Arabia in 1990 were still not released (because they never existed).

I cringe every time some 'hawkish' politician promotes the idea of sending troops to some foreign place in order to discourage aggression.
Look, a tiny such detachment is militarily irrelevant and politically no more relevant than diplomatic statements. A substantial, militarily relevant force such as Force Z on the other hand is a nice target for a coup de main. A huge forward-deployed military force such as the Russian pacific fleet of 1904 or the U.S. Pacific Fleet of 1941 might lose a war within hours or days.

The idea that tripwire forces are a deterrent is probably a symptom of arrogance, or of thinking of military forces too much as of representatives. Sure, they would deter if they represented the whole force's power, but all-too often in history the potential aggressor saw them more as an enticing isolated target than as equivalent of the whole thing. It's certainly a political idea, and flourishes best in absence of red teaming. Military minds would in my opinion tend to look at tripwire forces through the eyes of the potential aggressor, and see them also as targets, not only as respectable obstacles.

In short; tripwire forces work really well when they're not needed, and constitute a major strategic blunder if the potential aggressor is really offensively-minded. Tripwire forces are an expression of strategic stupidity. They should be eradicated from the political and military repertoires and vocabularies.



  1. I think that nowadays small forces deployed piecemeal are not for "trip-wire", but for waving the bloody shirt and as such they're useful.

  2. I would agree that tripwire forces are not useful from a military point of view. However, politically, they could accomplish a significant goal - to build support for war on both domestic and international level.

    For example, if two small countries have a border dispute, and third country supports one of them (the defender), the government of the third country might have a hard time gathering domestic and international support for the intervention if the aggressor attacks. A small tripwire force that would be deployed in such case would, if attacked, give the third country an excuse to intervene.

    Now, using own forces for such purposes, apart from being immoral (because own soldiers are likely to be killed or badly wounded), can also be very harmful if used by warmongers to drag a country in a stupid war. However, a government can use it to gather international support for a military intervention that would benefit the country (I can' think of any such example, though).

  3. Tripwire forces serve a purpose, but they HAVE to be expendable.

    The problem with Force Z (and much of the RN today) was that it was easy to destroy and we couldnt afford to lose it.
    "Trip wires" like the Falklands guard ship are inviting targets we cant afford to lose.

    Tripwires like NP8901 are a very different kettle of fish.
    They prevent "peaceful invasions". In that you couldnt just land a military police force and seize the area, arresting any locals who disagree, there has to be a surrender, on one side of the other, and probably shooting.
    By accepting the surrender of NP8901, Argentina accepted that the UK had exercised control of the area previously, and that Argentina had precipitated the war.

    If NP8901 had been wiped out, it wouldnt have trouble corporate*. The loss of Force Z ended the RN in East Asia until Tirpitz went under. The loss of a Daring would be a huge problem to any RN fleet.

    Or someting like that

    *Obviously the NP wouldnt be happy.

  4. I think, rax and leo summed it up. This seems to be what he so called pivot of the US is about in its naval context. Operationally irrelevant forces are being forward-deployed, so when things heat up, they provide the bruise to rally domestic support around government. Not everyone involved will see it that way, but thats what it amounts to.

    1. The U.S. routinely forward deploys carrier battlegroups. Even two or three of them in one region.
      I suppose the USN doesn't consider 3 CVBGs as expendable, even though it has many more.
      2 CVBGs are the equivalent of Force Z for the British in WW2.

  5. Looking at the context and specific environment of these deployments, doesnt that prove the point? The US are actually quite careful about when to make CVBGs part of such moves. Two or three carriers have lately been deployed only in one region at the same time, against a potential/declared enemy, who is hardly capable of inflicting any serious, let alone crippling damage on the USN, despite the rhetoric on both sides of that trench. On the other hand, such a deployment has not been seen for quite a while in the Pacific in any context, that could be misunderstood by, say China (no Taiwan-strait cruises anymore! Certainly no two or three CVBGs in the South China Sea in the near future).

    Some folks are getting concerned about the recent antics in North Korea. Incidentally the US are having trouble even deploying a single carrier group to the region on anything like a near-term sustainable basis.
    Which is why I brought up the pivot, which, looking at the hard numbers, is essentially a sham...a supposedly strategic shift, that in its much touted increase of presence depends entirely on LCS (two hulls are supposed to be forward-deployed permanently under current plans) and a very limited number of amphibious forces (generally one extra LPD or LHA) in addition to whats there already. Sure, the US is short on cash these days, but frankly I think, there is a rational reason too in, say, putting more than one CVBG into too close a range of mainland China on an extended basis.

  6. The problem I have with this argument is that you discard the idea by only considering instances where it has failed without also providing an argument for why there cannot be instances where it has succeeded.

    As I understand it the idea of the tripwire is to prevent attacks, so the sign that it does work would be that war is prevented or at least carried out somewhere else. In any case, a successful tripwire should to the casual observer look pretty much identical to a waste of time, should it not?

    So my point is this: what exactly are you talking about when you say "tripwires"?

    (Somewhat related, which are the conflicts that did not result in open war that you consider when judging the effectiveness of different deterrence strategies Sven?)

    1. By "tripwire force" I mean the forward deployment of forces too weak to defend themselves for the purpose of deterrence.

      It's logically not possible to prove that something cannot be, so I don't try it.

      What I'm criticising is the systemic political neglect of the military risk to the forward-deployed forces and the systemic political neglect of the war-provoking nature of forward-deployed forces (coup de main).

      The recipe may have succeeded at times, but that's would not a decisive argument either way. I argue that the political expectation that tripwire forces deter is more likely wrong than true.

      There can't be a conclusive study of this subject in a blog post, and my approach is simply to voice my opinion and deliver at least one powerful example of failure to make readers think about it.

    2. I would add that the clear primacy of the purely political purpose of these trip-wire forces over the military is very well demonstrated by one of your examples; the deployment of elements of the US 82nd Airborne Division to the Kuwait-Saudi border in August 1990.

      The inability of the paratroops to successfully defend against a deliberate attack by an armored force wasn't just a question of the technical capability of the then-issued BGM-71 TOW, M47 Dragon, and M72A2 LAW (I don't recall whether the 3/73rd Armor deployed in early August - I suspect that it and it's M551 Sheridan tanks arrived somewhat later in the month). The U.S. Army knew from tactical training that the paras couldn't do it.

      Our tactic for armored assault was called an "Airborne Anti-Armor Defense" or AAAD and centered around supposedly-mutually-supporting strongpoints where the Echo Companies and the battalion anti-tank platoons (all with TOW-armed M151s) would provide the AT fires while the infantry battalions would hold a mine-and-wire fortified perimeter defense. These were supposed to be supported by divisional and XVIII Corps artillery.

      In theory they worked during the REFORGER exercises, but when they were tried in a desert environment at the National Training Center at Ft. Irwin the results were uniformly poor; the OPFOR stood off and pounded the exposed TOW positions with artillery and then overran the surviving infantry with armor once the AT systems were sufficiently degraded. The AAAD never (to my knowledge) worked as planned in the desert.

      So the guys were, as they described themselves, "speed bumps", merely there to assure the Saudis that the U.S. had their back, and the U.S. military planners surely know that, as they reinforced the paras as quickly as possible. Had the Iraqis truly intended to attack the results would have been brief and ugly for the 82nd...