The truncated icosahedron geometry employed for the symmetrical shockwave compression of fission implosion devices.

The simplest nuclear weapon is commonly known as a gun-type device, because it achieves critical mass by forcing together two sub-critical masses of uranium through a mechanism very much like a gun that shoots a smaller wedge-shaped sub-critical mass into a larger sub-critical mass. This was the design of the “Little Boy” Hiroshima atomic bomb. The next level of complexity in nuclear weapon design was the implosion device, which relied upon conventional explosives to symmetrically compress a larger reflector/tamper sphere of U-238 into a smaller sphere of Pu-239, with a polonium-beryllium “Urchin” initiator at the very center. The scientists of the Manhattan project were so certain that the gun-type device would work that they didn’t even bother to test it, so the first nuclear device to be tested, and indeed the first nuclear explosion on the planet, was the Gadget device designed to be the proof of concept of the more sophisticated implosion design. It worked, and this design was used for the “Fat Man” atomic bomb dropped on Nagasaki.

These early nuclear weapon designs (conceptually familiar, but all the engineering designs are still very secret) are usually called First Generation nuclear weapons. The two-stage thermonuclear devices (fission primaries to trigger fusion secondaries, though most of the explosive yield still derives from fission) designed and tested a few years later, known as the Teller-Ulam design (and tested with the Ivy Mike device), were called Second Generation nuclear weapons. A number of ideas were floated for third generation nuclear weapons design, and probably many were tested before the Nuclear Test Ban Treaty came into effect (and for all practical purposes brought an end to the rapid development of nuclear weapon design). One of the design concepts for Third Generation nuclear weapons was that of a shaped charge that could direct the energy of the explosion, rather that dissipating the blast in an omnidirecitonal explosion. There are also a lot of concepts for Fourth Generation nuclear weapons, though many of these ideas are both on the cutting edge of technology and they can’t be legally tested, so it is likely that little will come of these as long as the current test ban regime remains in place.

According to Kosta Tsipis, “Nuclear weapons designed to maximize certain of their properties and to suppress others are considered to constitute a third generation in the sense that their design goes beyond the basic, even though sophisticated, design of modern thermonuclear weapons.” These are sometimes also referred to as “tailored effects.” Examples of tailored effects include enhanced radiation warheads (the “neutron bomb”), so-called “salted” nuclear weapons like the proposed cobalt bomb, electro-magnetic pulse weapons (EMP), and the X-ray laser. We will here be primarily interesting in enhancing the directionality of a nuclear detonation, as in the case of the Casaba-Howitzer, shaped nuclear charges, and the X-ray laser.

What I would like to propose as a WMD is the use of multiple shaped nuclear charges directing their blast at a common center. This is like a macroscopic implementation of the implosion employed in first generation nuclear weapons. The symmetry of implosion in the gadget device and the Fat Man bomb employed 32 simultaneous high explosive charges, arranged according to the geometry of a truncated icosahedron, which would result in a nicely symmetrical convergence on the central trigger without having to scale up to an unrealistic number of high explosive charges for an even more evenly symmetrical implosion. (The actual engineering is a bit more complicated, as a combination of rapid explosions and slower explosions were needed for the optimal convergence of the implosion on the trigger.) This could be employed at a macroscopic scale by directional nuclear charges arranged around a central target. I call this a macro-implosion device. In a “conventional” nuclear strike, the explosive force is dissipated outward from ground zero. With a macro-implosion device, the explosive force would be focused inward toward ground zero, which would experience a sharply higher blast pressure than elsewhere as a result of the constructive interference of multiple converging shockwaves.

A partially assembled implosion device of a first generation nuclear weapon.

The reader may immediately think of the Casaba-Howitzer as a similar idea, but what I am suggesting is a bit different. You can read a lot about the Casaba-Howitzer at The Nuclear Spear: Casaba Howitzer, which is contextualized in even more information on Winchell Chung’s Atomic Rockets site. If you were to surround a target with multiple Casaba-Howitzers and fire at a common center at the same time you would get something like the effect I am suggesting, but this would require far more infrastructure. What I am suggesting could be assembled as a deliverable weapons system engineered as an integrated package.

A cruise missile would be a good way to deliver a macro-implosion device to its target.

There are already weapons designs that release multiple bomblets near a target with each individual bomblet precision targeted (the CBU-103 Combined Effects Munition, more commonly known as a cluster bomb). This could be scaled up in a cruise missile package, so that a cruise missile in approaching its target could open up and release 12 to 16 miniaturized short-range cruise missiles which could then by means of GPS or similar precision location technology arrange themselves around the target in a hemisphere and then simultaneously detonate their directed charges toward ground zero. Both precision timing and precision location would be necessary to optimize shockwave convergence, but with technologies like atomic clocks and dual frequency GPS (and quantum positioning in the future) such performance is possible.

A macro-implosion device could also be delivered by drones flown out of a van.

A similar effect could be obtained, albeit a bit more slowly but also more quietly and more subtly, with the use of drones. A dozen or so drones could be released either from the air or launched from the ground, arrange themselves around the target, and then detonate simultaneously. Where it would be easier to approach a target with a small truck, even an ordinary delivery van (perhaps disguised as some local business), as compared to a cruise missile, which could set off air defense warnings, this would be a preferred method of deployment, although the drones would have to be relatively large because they would have to carry a miniaturized nuclear weapon, precision timing, and precision location devices. There are a few commercially available drones today that can lift 20 kg, which is probably just about the lower limit of a miniaturized package such as I have described.

The most elegant deployment of a macro-implosion device would be a hardened target in exoatmospheric space. Currently there isn’t anything flying that is large enough or hardened enough to merit being the target of such a device, but in a future war in space macro-implosion could be deployed against a hard target with a full spherical implosion converging on a target. For ground-based targets, a hemisphere with the target at the center would be the preferred deployment.

In the past, a nation-state pursuing a counter-force strategy, i.e., a nuclear strategy based on eliminating the enemy’s nuclear forces, hence the targeting of nuclear missiles, had to employ very large and very destructive bombs because nuclear missile silos were hardened to survive all but a near miss with a nuclear weapon. Now the age of land-based ICBMs is over for the most advanced industrialized nation-states, and there is no longer any reason to build silos for land-based missiles, therefore no reason to pursue this particular kind of counter-force strategy. SLBMs and ALCMs are now sufficiently sophisticated that they are more accurate than the most accurate land-based ICBMs of the past, and they are far more difficult to find and to destroy because they are small and mobile and can be hidden.

However, hardened, high-value targets like the missile silos of the past would be precisely the kind of target one would employ a macro-implosion device to destroy. And while ICBM silos are no longer relevant, there are plenty of hardened, high-value targets out there. A decapitation strike against a leadership target where the location of the bunker is known (as in the case of Cheyenne Mountain Complex or Kosvinsky Kamen) is such an example.

This is, of course, what “bunker buster” bombs like the B61 were designed to do. However, earth penetrating bunker buster bombs, while less indiscriminate than above ground bursts, are still nuclear explosions in the ground that release their energy in an omnidirectional burst (or perhaps along an axis). The advantage of a macro-implosion device would be that the focused blast pressures would collapse any weak spots in a target area, and, when you’re talking about a subterranean bunker, even an armored door would constitute a weak spot.

I haven’t seen any discussion anywhere of a device such as I have described above, though I have no doubt that the idea has been studied already.

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Grand Strategy Annex

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One of the consistent Cold War nightmares feared in the West was a massive Warsaw Pact armored spearhead into Western Europe. I discussed this a few days ago in Choke Points and Grand Strategy in relation to the Fulda Gap, which is one of the few geographical opportunities for a massive armored assault from east to west in Germany. This scenario so captured the imagination of Cold War military planners that NATO was largely constructed to counter such a Soviet armored thrust — a brute force frontal invasion expected from a regime that made no attempt to disguise its brutality in Hungary in 1956 and Czechoslovakia in 1968. NATO plans were dominated by this nightmare, and much of NATO strategic doctrine can be derived it. For example, NATO’s repeated refusal to pledge “no first use” of nuclear weapons was entirely a matter of knowing Soviet superiority in armor. The worry was that if NATO forces could not stop a conventional assault with conventional means, it would have to resort to the use of tactical nuclear weapons (TNW) on the battlefield. This was also (in part) the impetus for the development of the neutron bomb, which could have spared much bomb damage to Western Europe even while stopping massed Soviet armor pouring through the Fulda Gap.

Soviet mechanized armor rolled into Budapest in 1956; Cold War planners feared the same fate for West Germany.

It will be immediately understood, then, that the dreaded mechanized armor duel in and over Western Europe was never conceived by NATO as a symmetrical peer-to-peer engagement. NATO possessed TNW and would not say that it would not use this. Thus TNW, despite their tactical character, had a strategic role as well. This strategic deterrent to a conventional Soviet thrust into Western Europe was given credibility by the development of miniaturized TNW (notably the W-48 and the W-54) and even miniaturized delivery systems (The Davy Crockett). Perhaps just as importantly, NATO did not seek parity in mechanized armor, which would have also required parity in crews, which would in turn have required an even more massive US troop presence, or European tank crews.

Late Soviet military technology: the VA-111 Shkval supersonic torpedo, skill a formidable counter-measure to large, expensive ships.

We think of asymmetrical warfare when we think of terrorism and insurgency and revolution, but asymmetrical warfare has been central to conventional engagements between great powers, and was central to the Cold War. In addition to the asymmetry in mechanized armor in Western Europe, there were many other notable asymmetries. The Soviet Union and the Warsaw Pact made no attempt to engage the US and NATO at peer-to-peer parity on the world’s oceans. The US maintained a carrier fleet that could patrol all the world’s oceans, while NATO allies Great Britain and France also operated aircraft carriers. Instead of attempting to achieve parity in carriers, the Soviet Union developed hypersonic torpedoes (VA-111 Shkval) and ship-to-ship missiles (SS-N-22 Moskit) that, if employed in sufficient numbers, might well have neutralized these carrier assets.

Russian made 'Sunburn' supersonic anti-ship missile.

There was also asymmetry in strategic nuclear arsenals. The Soviet Union eventually (though not yet at the time of the so-called “missile gap”) had far more land-based ICBMs that the US. The US accepted this, but for its own strategic security relied on the “tripod” of land-based ICBMs, the bombers of the Strategic Air Command (SAC) under Curtis LeMay, and, in the later stages of the Cold War, when it became technologically possible, nuclear submarines mounting sea-launched ballistic missiles. This last leg of the tripod is a tale of asymmetry and competition in itself, since the Soviet Union did not concede the submarine asymmetry, but invested considerable resources in at least trying to catch up with NATO superiority. It took the Soviets longer to build missile boats, and when they built them they were louder and therefore easier to track, but they did build them, and once their spies told them that NATO simply listened for their noisy missile boats, they improved the stealth profile their subs.

Members of a Strategic Air Command B-52 combat crew race for their always ready-and-waiting B-52 heavy bomber. Fifty percent of the SAC bomber and tanker force is on continuous ground alert, ready to be enroute to target within the warning time provided by the ballistic missile early warning system. One of the bomber's two hound dog missiles is shown in the foreground. (U.S. Air Force photo)

Before the Cold War, in the most catastrophic of all conventional wars, World War II, there were also significant asymmetries. The Germans (like the Soviets later, both being continental land powers) had superior land forces, and as a result they conquered continental Europe. But early in their preparations for war they neglected to build a four-engine heavy bomber. In effect, the Germans conceded the bomber to the British. Once the Nazis occupied the whole of Western Europe, Britain had no way to strike back at the Nazis other than to wage unrestricted bombing campaigns against the Germans. This they did, with devastating results (I have called this the possible war for the British at the time). By the time the Germans realized their mistake, it was too late to build a heavy bomber, although when the Germans began to develop jet aircraft, Hitler repeatedly insisted that it should be built as a small bomber rather than as a fighter. There was by this time substantial public feeling against the mass destruction of German cities, and Hitler thought he needed to do something about it. Ultimately, the task fell to the so-called “vengeance weapons,” the V-1 and the V-2.

V-2 single stage ballistic missile

V-2 single stage ballistic missile

Also during the Second World War, as the British were waging an unlimited air war against the Germans, the Germans were waging unlimited submarine war against the allies. Once the Bismark was sunk, and Dönitz later became Großadmiral, the German surface navy was essentially abandoned and all crews were assigned to U-boats. Since peer-to-peer submarine combat was neither effective nor feasible at this stage of technological development (thought it became feasible during the Cold War), the Allies, who had the technological and industrial means to seek submarine parity, did not seek parity, but instead sought the development of anti-submarine warfare (airplanes with radar turned out to be highly effective in this role, e.g., the B-24 Liberator Mk.VI).

From these numerous twentieth-century examples, it is obvious that asymmetrical warfare is not a strategy pursued exclusively by poor, poorly equipped, and disadvantaged forces who seek an advantage that cannot be obtained through conventional means, which in this context might be understood as symmetrical means, but has been consciously pursued by great powers. The instances of asymmetry cited above could be characterized as military equivalents to comparative advantage. During the Cold War, it was in the interest of NATO to leverage its comparative advantage in technology, employing its technology against Russian numbers and brute force. The Soviets knew they could not compete peer-to-peer on technology, so it sought to neutralize NATO’s technological advantage with massive mechanized armor assets as well as cheap and plentiful counter-measures to advanced and expensive weapons.

Soviet armor assets didn't help the USSR much in Afghanistan.

Understood in this context, there has been no “rise” in asymmetrical warfare, and we are now no more living in an age of unconventional, asymmetrical warfare than any previous age. Asymmetrical warfare is a perennial aspect of warfighting, and represents a gradient of war that will be always be a part of military calculation. If objectives cannot be obtained the simplest, most straightforward way, then an oblique way will be found, and it is likely that this indirect approach to one and the same objective will be unconventional and asymmetrical.

And there is much to be said for unconventional warfare. It could be argued that those who possess an obvious advantage (which is itself an asymmetrical situation) are likely to become unimaginative in their planning. I argued this point in Choke Points and Grand Strategy. Thus the more “advanced” party to a conflict might well end up relying on brute force, whereas those who perceive themselves to be at a disadvantage may seek an innovative way to attain an objective without a frontal assault relying on brute force.

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Grand Strategy Annex

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