Interdiction today

Back in World War Two, fighter-bombers, light bombers, Stukas and more or less armoured Shturmoviks attacked the difficult ground targets; supply transports on the ground (rail, trucks, horse carts), troops on the march and deployed troops.

These small targets were impossible to detect and identify from high altitude, were difficult to hit, moving (= position not known when the aircraft took off) and at least troops on the march were even dispersing and firing back in reaction to attacks.

The munitions used were machine gun bullets, bombs of different kinds and especially late in the war cluster bombs and unguided rockets.

It was possible to use spiked bombs to leave a bomb as a mine at a railway track, and railway traffic was generally quite easily disturbed because of the indefensible, exposed static rails. Trucks weren't ubiquitous back then, so railway traffic was most important in the rear areas. Most ground attack aircraft on the Eastern Front didn't penetrate deeper than 10 or 50 km, though. It was usually more efficient (fuel, pilots) and less risky to fly two short incursions than one deep one.

The one thing that did not change much from 1944 to 2012 is the continent. Landscapes changed (especially by urbanisation), but railway networks are still similar and the size of the territories did not change (except the coastlines).
Modern army logistics changed more; logistics are much more about heavy trucks than in '44; railway connection got busted? No problem, just use more trucks. Many armies rely almost entirely on truck logistics anyway. We can do this easily, thanks to millions of heavy trucks in Europe. Back in 1944 a few thousands of much less capable trucks was a major effort.

So nowadays we couldn't cut off supply traffic (do interdiction) so well because
a) the vulnerable railways can easily be substituted
b) there's a practically endless supply of capable trucks
c) modern 24/7 attack sensors make the night no less dangerous than the day, so the enemy is not provoked to constrict his supply runs to the night. They just keep moving forward, damn the torpedoes bombs.

Supply interdiction would likely only have a very short-term effect, by producing supply delays. A rare exception would be a main supply route on land into Lithuania because of an extreme shortage of roads and anything resembling roads.

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What about troops on the march?

Today's ground troops are at least motorized, if not mechanised. A brigade column may be many kilometres long, but it would have spacing between vehicles (50-100 m, it depends) and the column would usually reach its destination within a few hours.
How many attack planes would engage this column in two or three hours? Certainly only a fraction of those which are in the air during that period, for most will be on combat air patrol, suppression of enemy air defence, reconnaissance or structure attack mission (with poorly suited munitions) or be forced to abort due to aerial opposition.
Back in WW2, all pilots had the choice whether to strafe a column or not, for their machine guns were adequate weapons. Today's combat aircraft have 20-30 mm autocannons, but only the A-10 has a really meaningful amount of ammunition on board. The others could not strafe much better than an average WW2 fighter; clearly unsatisfactory considering the inexhaustible supply of vehicles and the small quantity of modern combat aircraft.
What's more; back in WW2 troops on the march were rarely well-armed to fend off air attacks. Nowadays there's the ubiquitous ManPADS missile threat and there are still SPAAGs (anti-air vehicles), too. The old strafing attack is simply not worthwhile any more against capable opposition.

Well, maybe you remember the photos of burned-out wrecks from Iraq's withdrawal from Kuwait in 1991.
* no modern ManPADS
* no effective SPAAGs
* no concealment
* only one major route available
* long-lasting troops movement
* poor march discipline (spacing)
* extremely lopsided conflict in general (training, equipment)

As so much else that happened on Arabian terrain, it's simply not representative for what would happen in higher developed warfare on more cluttered terrain. Consider those photos as as representative for modern air interdiction as was the Great Marianas Turkey Shoot for modern air war.

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Last category; troops in the field (close air support).

Clearly, air power has huge challenges in CAS because of fratricide and generally chaos problems. It helps a bit that ground observers help air power, but the more close air power is bound to ground observers, the more it becomes a substitute for artillery. 100 million € aircraft are a really, really expensive substitute for artillery. That is part of the reason why  there won't be enough CAS missions to satisfy high expectations.
Air force leaders are not inclined to allocate much air power to CAS in a conventional campaign because it's rather inefficient and there are too many fixed demands (combat air patrols et cetera). The exception are emergency concentrations of combat aircraft on CAS missions on the spot of a local crisis (=battle not yet won; see Battle of Khafji).

Why did I write this?
I've encountered more than once the idea that air power has become so powerful, so accurate, so all-seeing today that it could, no, WOULD wipe out entire brigades at ease and cut off supply as well.
This belief was already present in "Air-Land Battle" doctrines, which were "very optimistic" about air power.
I don't trust this idea at all. The now effective defence against simple low-level attacks, the huge supply of motor vehicles, the complexity of the clustered European terrain in comparison to Arabian (half) deserts, the moderate quantity of combat aircraft and the rather specialised munitions even of multi-role combat aircraft oppose the idea of the all-powerful tactical air.

True, a brigade could be wiped out from the air IF a hundred Typhoons laden with almost only Brimstone missiles attack it. The problem is that a Polish infantry division was practically knocked out at a railway station by a Stuka wing in September 1939 as well, a feat that rarely had equals later on. Perfect storm events such as this are rare and should not dominate our appraisal of tactical air power's utility.

S Ortmann


  1. From a numbers point of view, WW2 tactical air was often not very effective. The hit rate for rocket firing Typhoons was something like 4%. They rarely stopped reinforcements from reaching the front, and I am not aware of them ever severing a supply line.

    But Dupey noted that in battles where air power was present in late war scenarios, the western allies generally won, when it was not present (generally because of weather) they did not.

  2. Building on Russell 1200's comment: It's been noted that for suppressive effect, that 4% aerial rocket hit rate was evidently sufficient. As has been posted here before, for example, a 10% chance of getting hit is entirely unsatisfactory to the infantryman because he rarely gets back up after such a hit. Depuy's note may stem from the ability of Allied air to pin units in place where artillery and then direct fire weapons took a much higher toll: German manoeuvre in NW Europe was limited by the constant presence of the tactical air forces and this held them in places where very systematic British Commonwealth tactics could defeat them with fire. German tank units were particularly susceptible to this, apparently, and we see evidence of the same happening in the vicinity of Falaise: critical equipment is being pinned in place and its operators flee because they are prevented from moving by airpower and scared. So they reduce their target profile by ditching the artillery or the tank that draws so much fire and flee on foot.

    Air-Land Battle is largely predicated on separating echeloned formations from each other by imposing such delays, either by destroying critical routes or pinning units in place. Soviet air defence technology is capable of protecting formations on the move (not the ZRKs themselves, they halt to fire, but the formation they belong to keeps moving) largely to prevent just this from happening. Our perception of air defences is coloured by guys who can barely read being confronted with very complex 1960s/70s vintage Soviet SAM systems. There are accounts from PVO officers seconded to Arab forces as trainers, for example, that their students would start screaming "Allahu akhbar" instead of shooting at the radar contact, or after Israeli SEAD effects took hold, they'd get a contact and then simply run away from the system.

    Interdiction doesn't work in contemporary AOs either, even when things like the AH-64D with incredible imaging capability are watching individuals under circumstances where we have total air supremacy. Given that we can't stop an enemy unit from transporting mortars or heavy machineguns around in an Afghan village under conditions where the pilot has a minimal risk of being shot down, I don't think we can rely on airpower halting the movement of a battalion via a concealed route under the air cover of some very good SAM systems. We have no equivalent SAM systems, relying instead on fighters to control the sky. This might work, until the fighters' support infrastructure is destroyed.

  3. I dont get why you think roads cant be blown like railways.

    Cant speak for Germany, but the UK is a bottleneck.
    I had to detour THREE MILES to cross a ten foot road closure once.

  4. TrT, things change when you're allowed to drive through other people's lawn and even have engineer support.

    I consider E67 and 16/135 roads here
    as unusual bottlenecks.

  5. @russel: Look at the link (D&F, air attack paradox) in the text. Whatever lethality allied Tac Air had in '44,it sufficed to choke daylight movements. Nowadays we wouldn't choke daylight movements because the night isn't safe either. We could at bes suppress enemy movements while our strike packages are in the general area. That again requires that we allow the enemy to maintain at least some awareness about our strike packages and allow him to maintain radio comm - we attempt to suppress both capabilities with our SEAD campaigns.

    Modern air power isn't all that sound as it looks on the surface.

  6. So
    True, actualy, on the way home fromt that, I got off my scooter and pushed it along the pavement....

    But that was a scooter, not a HGV, and that was a no access sign, not a crater caused by a 2000lb earthquake bomb


    Its a long long way round if Gatley/Kingsway junction is hit by something big.

    Drop a big penetrator HE and bring the neighbouring houses down, nothings getting through until the engineers show up and clear a path.

    Theres dozens of junstions like that, just on my route home, how many engineers does the other side have?
    Half a dozen big bombs are going to leave a crater that isnt going to be filled in a few hours.

    I still think you underestimate the potential losses of a truck column being surprised by a couple of fighters, I wouldnt expect to see any RAF aircraft up without without at least three Brimstones, and one could easily carry twenty plus, thats a couple of companies dead.

    But yeah, over the grand scale of things, probably ignorable.
    Hence why I think we should be planning to attack roads, in a big way.

    Much bigger bombs of course, but the Tall Boy would create a crater 24 meters deep and 30 meters across.

    Enough to interdict Roads?
    Depends on the roads and the surround area I suppose

  7. Seriously, TrT, destruction or blocking of roads is not going to work out well in most cases.

    A couple roads in mountains as well as roads that can be buried under a traversing bridge may be exceptions, of course.

    If I was so interested in disrupting road traffic as you appear to be, I'd rather look up the details of the cluster munitions and AP mine ban treaties and look at what kind of mining of roads they allow for.

    Mines of this kind
    are reputed to miss fast-movers by not leading them enough, but such mines might still impair road traffic much more than ten times the weight in unitary bombs. M93 was meant t be scatterable (deployment by air).

  8. Assets capable of delivering huge bombs are scarce. There are, for example, a mere nineteen B2A bombers to cover the entire globe. The Russians have largely defeated LO/VLO shaping through the use of VHF-band radars (Nebo SVU, Vostok-E, et al) and have SAMs capable of killing fighters at extended ranges: large, slow targets such as B2A or B52 are much less of a challenge. It cannot be assumed that our electronic countermeasures will always defeat theirs, particularly when home-on-jam and IIR seekers are known to be employed on Russian missiles. Combined with their known doctrine of firing in pairs with dissimilar seeker types at the same target, to improve the probability of killing that target by forcing it to respond to two different threats, I believe our reliance on airpower is a fundamental mistake. The airspace will largely be denied to us in the face of these systems: I would like to be wrong about this, but from open source information it does not seem that I am.

    It is unlikely that scarce, vulnerable assets will be diverted to blow road junctions. Fighter-bombers will have to do it instead, and their sortie rate might require them to be assigned only the highest priority targets. Interdiction of logistics will probably fall behind slowing down a tank column, particularly as we have weak antitank defences (insufficient number of very fancy missiles and comparatively few tanks remaining)

    The Russo-Soviet approach would be to fire a large unitary HE warhead at it from a tactical-operational ballistic missile. Several were fired during the 08.08 war, but that wasn't against a peer opponent who could strike back with chemical or nuclear means at a ballistic missile launch.

    TrT, you might overestimate the ability of air to penetrate an area defended by a modern IADS. SO's comments regarding a 'basically bottomless pool of trucks' (to paraphrase) are accurate enough: those semis you see hauling flatbed trailers would be just as adequate for moving ammunition pallets and other supplies around as a dedicated military vehicle, though it would become more road-bound because of lesser cross-country mobility. In Europe, where the road network is extensive, this is less of a problem than in less well connected areas.

  9. Tall Boys were 5000lbers

    The F35C has SIX 2500lb pylons.
    The Typhoon has a 16500lb payload.

    You dont bombers to carry them anymore.

    "It is unlikely that scarce, vulnerable assets will be diverted to blow road junctions."
    If it pins a motorised rifle battalion for the few hours it takes to mount something to blow the trucks carrying them.

    But it rather depends who you are fighting, Sven, being German, cant see anything but Russia.

    Also, its not just road junctions, bridges would be a far more realistic target, as would tunnels, motorway on/off ramps and "sunk" motorways.

    At the end of the day, in the last hundred years, the UK has fought two wars in France, and one in west germany.

    We've fought a lot of wars elsewhere

  10. Those "other wars" are not worthy to be prepared for, though. They wouldn't be wars of necessity, but political adventures.

    There are indeed only two plausible scenarios for an actual war of necessity for Germany; one involves a conflict with present allies and the other involves Eastern Europe.
    The Arabs are kept at a distance by the Med and are no challenge for the next 10+ years while the Turks and Iranians are weak on their own, weak together and the Turks are presently allied with Germany.

  11. TrT; the theoretical load of combat aircraft is not helpful. a Typhoon with two Tall Boy equivalents (IF they would fit and allow for the AoA during take-off) would have an extremely short mission radius.

  12. 1. Strafing has not been the primary means of air interdiction for at least the last 50 years, yet the article acts as if it still is.

    2. Manpads and spaa vehicles for convoy are a threat, hence the development of the fast, low flying penetration bomber like the F-111 or Tornado IDS, preventing early detection and reducing time over target and hence vulnerability.

    3. While convoy dispersion and vehicle armouring may have increased, weapons capability has also increased. A single cluster bomb will scatter bomblets in a template hundreds of metres long, with each bomblet capable of disabling a vehicle if it hits.

    4. While aircraft taskings have increased, aircraft payload has also increased. Each F-111 can carry around a dozen cluster bombs. A single pair of F-111s would be all that's necessary.

    5. ISR capabilities have also improved considerably. Instead of needing to search for convoys by eye and flying around, a JSTARS style strike controller would handle the detection of such convoys. Greatly reducing mission time, which results in both reduced vulnerability and more flyable missions per day.

    1. 1. The typical interdiction activities that are not against convoys (bridge busting, railway net bombing) are of much less relevance today than in WW2 because of the motorisation of forces and supply.

      2. VShorAD was defeated by flying high, while flying extremely low was a dead end, particularly in face of capable opposing fighters.

      Points 3-5 are really optimistic, assuming hardware works as advertised.