The Student Room Group

Could Trident ever be used?

The hard left often proclaim that Trident could never be used, that if you have to use it you've already lost and so there's no point. While this is correct from the perspective of deterrence theory, I believe there are situations where we could envision using the Trident system.

First, I should say that the current missile system we use, Trident D5, was developed in the Cold War to provide to the submarine force a weapon that had the throw-weight (the total weight of warheads it can "throw" at the target) and accuracy of land-based ICBMs. Previously submarine-launched ballistic missiles were only good for city-busting; they could target something the size of a city (which worked very well for the submarine's forces role providing guaranteed retaliation), but they lacked the hard-target capability possessed by land-based missiles. They lacked the accuracy (Circular Error Probable, the radius of a circle within which a warhead will statistically hit 50% of the time) necessary to hit hardened command bunkers, nuclear missile silos etc.

Trident D5 changed that, and gave the submarine force a system that had the accuracy to hit these hard-targets, or any discrete target. And it is this ability to hit any target in the world (or at least on the Eurasian continent and Africa) within 30 minutes of receiving orders from the national command authority, and to hit it with a high degree of precision (Trident D5 can lay down a warhead within about 80 yards of the aimpoint) that makes Trident practically useful and a capability we should hold on to.

The other element here is UK Trident's "sub-strategic" capability. Most of the warheads are a British design based on the US W76 warhead, with a yield of around 100 kilotons (equivalent to 100,000 tons of TNT. For comparison, the atomic bombs that hit Hiroshima and Nagasaki were in the 15-20 kiloton range). However, the UK also maintains the capability to deliver a much lower yield warhead; it's been reported the UK version of the W76 is variable yield warhead (so-called "dial-a-yield"), so they can select the power of the warhead before firing it. The reported available yields are 0.3 kilotons, 10 kilotons and 100 kilotons. The 0.3 kiloton yield is particularly useful considering we have no idea of the future threats we might face.

An example scenario is imagine we received very time-sensitive intelligence that an ISIS base in a very remote part of Central Africa had developed a biological weapon, say a form of weaponised ebola. Or they had managed to cobble together a nuclear weapon. The intelligence tells us they are preparing to move this weapon in the next hour. In such a situation, we would have no conventional capabilities we could use to hit this target. It would take hours for an aircraft carrying bombs or an SAS team to prep for a mission then fly into central Africa. But we could use Trident; we could fire a missile with three warheads each set to a 0.3 kiloton yield (the equivalent of 300 tons of high explosive). These are not city-busting warheads that would kill million, I put in the numbers at nukemap and it provided these effects calculations

Fireball radius: 40 m (4,460 m²)
Maximum size of the nuclear fireball; relevance to lived effects depends on height of detonation. If it touches the ground, the amount of radioactive fallout is significantly increased.

Air blast radius (20 psi): 190 m (0.11 km²)
At 20 psi overpressure, heavily built concrete buildings are severely damaged or demolished; fatalities approach 100%.

Thermal radiation radius (3rd degree burns): 400 m (0.5 km²)
Third degree burns extend throughout the layers of skin, and are often painless because they destroy the pain nerves. They can cause severe scarring or disablement, and can require amputation. 100% probability for 3rd degree burns at this yield is 6.4 cal/cm2.

Air blast radius (5 psi): 470 m (0.68 km²)
At 5 psi overpressure, most residential buildings collapse, injuries are universal, fatalities are widespread. Optimal height of burst to maximize this effect is 210 m.

Radiation radius (500 rem): 0.68 km (1.44 km²)
500 rem radiation dose; without medical treatment, there can be expected between 50% and 90% mortality from acute effects alone. Dying takes between several hours and several weeks.


This strike would wipe the ISIS base off the map. But it wouldn't massively irradiate the local area or render it uninhabitable. It wouldn't effect towns five or ten kilometers away. It's impossible to say what kind of threats to the UK will emerge over the next 40 years. No-one predicted the rise of ISIS, no-one can say what threats we will face in terms of biological weapons proliferation, nuclear weapons, and other threats. It makes sense for us to retain the only weapons system that gives us the absolute capability to strike a target thousands of miles away within tens of minutes with significant force.

Only slightly related, I thought I'd embed this cool video I found of French nuclear tests in the Pacific. The most awesome one is the last one, a weapons development test in 1996 for their TN75 warhead (the last nuclear test by a major power). It's incredible how it detonates under the lagoon

[video="youtube;7NEa-qDqUCU"]https://www.youtube.com/watch?v=7NEa-qDqUCU[/video]
(edited 7 years ago)

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the enemy has to believe it will be used. there are some in the military who dont believe it would be. I think and hope it would be. In any event the amount of nuclear explosions is most likely to cause a nuclear winter as well as mass radiation which will kill everyone except the cockroaches.
Original post by 999tigger
the enemy has to believe it will be used. there are some in the military who dont believe it would be. I think and hope it would be. In any event the amount of nuclear explosions is most likely to cause a nuclear winter as well as mass radiation which will kill everyone except the cockroaches.


The threat of nuclear winter has been very much overrated. By the early 1980s, both the US and Soviet Union focused their nuclear forces on the "counterforce" rather than "countervalue" mission. That is, their nuclear weapons were aimed at enemy missile silos, bomber bases, hardened command bunkers, communications satellite receivers, high-band radars and so on (all these are counterforce targets.. countervalue, the strategy from the earlier Cold War due to less accurate weapons, focused on obliterating enemy cities).

Some good calculations suggest that in a moderate counterforce exchange, each side would have taken about 8 million casualties. Remember that since 1945 there have already been something like 2500 nuclear tests; during the Cold War the nuclear defence establishments on both sides were engaged in a continuous programme of designing, testing and refining weapons designs and concepts.

As for the credible threat of use, there are steps short of nuclear war we could take to signal to our adversary that they have gravely miscalculated Britain's resolve and that they should back down or face a massive strike. One way to do this would be to restart a limited programme of atmospheric nuclear tests; if the UK was to send a second Trident submarine to sea and to have it set off half a dozen warheads in the South Atlantic, that would send just such a signal. Our adversaries have to fear the madman (as Nixon said)
Reply 3
It's a tool. Any tool could be used.

The better question is "would it be used?".





As an aside, here's a question I've been pondering and one I don't actually know the answer to; ignoring the cost for a moment, what's stopping us replacing the nuclear warheads of the ICBMs with conventional explosives? We'd then have an extraordinarily potent tool for instant reaction over incredible distances but in a non-'ending of the world' way. Not too crazy, no? The argument that "these weapons would never be used" would instantly disappear, because while we may not use the nuclear warheads, we could definitely use the missile body.
(edited 7 years ago)
Original post by Drewski
It's a tool. Any tool could be used.

The better question is "would it be used?".


That's kind-of the point of my thread... your response takes us no further than we already are with the title question.

The sub-strategic variable yield capability provides us with an eminently usable and useful system. It also makes it a more credible deterrent; if we only had, say, one megaton warheads then the threshold for use would be so high that our adversary could be fairly confident that actual use is so unlikely as to nullify the deterrent value.

The 0.3 kiloton variable option lowers the threshold for potential use in the case of major nation-state adversaries (strengthening deterrence), and provides us with a capability to deal with immediate, time-sensitive threats in the future in a way that doesn't commit us to using full-yield nuclear weapons.
The final orders written by the last Prime Minister in current office, are contained in a letter to the captain/s of the boats on patrol. Those orders are top secret and will be executed when the launch codes are authenticated in the event of war. The contents will only be known when all diplomatic and other avenues have failed and that the UK has been attacked with nuclear weapons when the only thing left are the subs at sea..

The whole point of deterrence is not knowing. The enemy must believe that if they ever launch a first-strike, they are playing Russian Roulette with a few dozen nuclear warheads aimed at them. There may, or there may not, be a nuclear retaliation.

In other words, MAD as a deterrent still stands. But we must have the capability at sea ready to go in order to keep the deterrence as our insurance policy.
(edited 7 years ago)
Reply 6
Original post by BeastOfSyracuse
That's kind-of the point of my thread... your response takes us no further than we already are with the title question.

The sub-strategic variable yield capability provides us with an eminently usable and useful system. It also makes it a more credible deterrent; if we only had, say, one megaton warheads then the threshold for use would be so high that our adversary could be fairly confident that actual use is so unlikely as to nullify the deterrent value.

The 0.3 kiloton variable option lowers the threshold for potential use in the case of major nation-state adversaries (strengthening deterrence), and provides us with a capability to deal with immediate, time-sensitive threats in the future in a way that doesn't commit us to using full-yield nuclear weapons.


See my edit, a part 2.
Reply 7
Original post by Drewski
It's a tool. Any tool could be used.

The better question is "would it be used?".





As an aside, here's a question I've been pondering and one I don't actually know the answer to; ignoring the cost for a moment, what's stopping us replacing the nuclear warheads of the ICBMs with conventional explosives? We'd then have an extraordinarily potent tool for instant reaction over incredible distances but in a non-'ending of the world' way. Not too crazy, no? The argument that "these weapons would never be used" would instantly disappear, because while we may not use the nuclear warheads, we could definitely use the missile body.


You have the same problem as with Nuclear Cruise Missiles. If we went to war with a nuclear power, or even against a non-nuclear power that was geographically close to one, an incoming missile strike could be mistaken for a nuclear one, leading to a similar response. If you are saying we could remove the nuclear warheads and simply have a conventional weapon instead, I don't see much of an advantage over a cruise missile, but with a much higher cost per missile.
Original post by Drewski
I
As an aside, here's a question I've been pondering and one I don't actually know the answer to; ignoring the cost for a moment, what's stopping us replacing the nuclear warheads of the ICBMs with conventional explosives?


There are very good technical reasons for this. The Trident missile, once launched, flies on a suborbital trajectory into space; once over the target (and the rocket boosters have dropped away), what you have left is the "warhead bus", a sort of single-use satellite with little thrusters on it. It manoeuvres into position and pops off the multiple warheads (up to 12 on Trident) so that they re-enter the atmosphere at the precise location and angle that they will hit their target.

The upside of this delivery method is speed; it takes less than 30 minutes from launch to target destruction. The downside is that there really is a minimum level of accuracy beyond which research dollars are essentially thrown away; the turbulence of re-entry, the high wind speeds and pressures etc, mean you will never be able to get cruise missile or smart bomb levels of accuracy. Modern smart bombs have a Circular Error Probable of around 3 meters. SLBM warheads have a CEP of about 70 meters.

The Trident warhead bus throws off a dual package; it is the W76 warhead (called the "physics package", the bit that actually goes bang) and it is encased in the Mk4 re-entry body, an advanced mini-spacecraft thing with advanced radars so it detonates at the perfect height, heatshields like the space shuttle, and mini-thrusters to impart spin (like a bullet out of a rifle or a cricket ball) to increase accuracy. Once you have all those systems out of the way, you are left with around 200 lbs for the warhead. 200 lbs of high explosive detonated 80 meters away from the target would do nothing.

Sorry for the long technical explanation but it is an issue that has been looked into before, and they concluded for these reasons that high explosive in an ICBM/SLBM re-entry body simply doesn't deliver the explosive power x accuracy you need to damage a target reliably. It would be very hit and miss
This is a really good thread, there's a LOT of misinformation about nuclear weapons. People don't realise that not every nuclear warhead is capable of taking out a city and that's not the only use for it. I mean look at the Davy Crockett. Hell, with the clean bombs we have now even fallout isn't that big an issue.

The biggest issue with using a nuke in combat today, would be the political ramifications. That said, I do believe they should be used only as a last resort/emergency type thing. You certainly don't want nukes to become "normalised" like other bombs are.
Original post by Aj12
You have the same problem as with Nuclear Cruise Missiles. If we went to war with a nuclear power, or even against a non-nuclear power that was geographically close to one, an incoming missile strike could be mistaken for a nuclear one, leading to a similar response. If you are saying we could remove the nuclear warheads and simply have a conventional weapon instead, I don't see much of an advantage over a cruise missile, but with a much higher cost per missile.


It's true that there is the issue of Russia mistaking a conventional launch for a nuclear attack, this was a major objection raised against the Prompt Global Strike programme that proposed putting HE warheads on ICBMs during the Bush years. Personally, I don't think that's so much of an issue given in the kind of scenarios I'm talking about (say, a launch against an African or Middle Eastern target) you'd call the Russians on the hotline to give them advanced warning.

The major obstacle is technical; dealing with the low relative accuracy of ICBM/SLBM re-entry bodies for the amount of high explosive delivered (see my comment above). To get around this the US did consider whether a new re-entry body could be developed that has a ramjet engine and a terminal seeker; this is probably outside the UK's price range but could be an option in the future.
Original post by Aj12
I don't see much of an advantage over a cruise missile, but with a much higher cost per missile.


Cruise missiles in UK order of battle:
Tomahawk, range ~1500miles
Storm Shadow, range ~300miles

Range of D5 = 7,500miles

And there exists plenty of cruise missiles which can be either conventionally or nuclear armed - that have been used in conflicts without adverse political reactions.

The only people who would be adversely worried would be those who can detect launches as they happen. That would be limited to the US, Russia and China. Forewarning them that we were about to launch a conventionally armed ICBM would be child's play.

Yes, I know the cost would be high, but it would give us instantaneous reaction to virtually anything on the globe - something nobody has. Can't be that crazy an idea. Lowering the CEP using GPS is also technically possible - even if also expensive.
(edited 7 years ago)
Original post by Zargabaath
This is a really good thread, there's a LOT of misinformation about nuclear weapons. People don't realise that not every nuclear warhead is capable of taking out a city and that's not the only use for it. I mean look at the Davy Crockett. Hell, with the clean bombs we have now even fallout isn't that big an issue.

The biggest issue with using a nuke in combat today, would be the political ramifications. That said, I do believe they should be used only as a last resort/emergency type thing. You certainly don't want nukes to become "normalised" like other bombs are.


Thanks very much, I really appreciate that :smile:

I completely agree regarding normalisation of nukes, my own view is that the 0.3 kiloton yield used against a time-sensitive target would only be used in the most extreme circumstances where its use is designed to end a major biological or nuclear proliferation risk or to pre-empt an attack using nuclear or biological weapons. They would only be used in the sort of circumstances where the world could understand why we resorted to such extreme measures.

Regarding low-yield weapons, the W48 is most impressive. It has a 0.072 kiloton yield (72 tons HE equiv), and it's tiny. Imagine fitting a plutonium implosion physics package in this tiny artillery shell, and engineering it to tolerate the 10,000G forces of being blasted out of a cannon (pic below)

A thoughtful post from the OP. Minor critique is that it's a bit of a chunk to get through but worth the read. In response, amazingly, I've actually bothered composing a proper reply.

I, for one, am grateful for the Vanguard class submarines patrolling the waters silently protecting our land.

I believe they would be used in response to an all-out nuclear attack on the UK, simply because it would be an almost-automatic response from our subs if we knew where the missiles came from. That said, I'm not actually sure how much autonomy the Captain of nuke sub gets in terms of whether to fire the missiles if the UK is nuked and there's no other chain of command. Let us hope and pray, we never have to find out. I would assume his authority is absolute depending on the content of the "Letter of last resort."


In terms of nuclear warheads being fired for the completion of non-nuclear strategic aims it's very very doubtful. A nuclear first-strike is almost impossible to justify on so many levels:

- Firstly, it's a massive escalation of the situation even with a low yield weapon.

- Secondly, to get the certainty of intelligence necessary to launch a strike of that magnitude is almost impossible. Remember Iraq? Intelligence can be flawed, manipulated or flat-out wrong.

- Thirdly, even ISIS having a nuclear weapon is a very different scenario from it being enough of an immediate threat to the UK to justify a nuclear pre-emptive strike they have no means of delivery that would make the threat imminent.

SS
(edited 7 years ago)
Original post by Drewski

The only people who would be adversely worried would be those who can detect launches as they happen. That would be limited to the US, Russia and China. Forewarning them that we were about to launch a conventionally armed ICBM would be child's play.

Yes, I know the cost would be high, but it would give us instantaneous reaction to virtually anything on the globe - something nobody has. Can't be that crazy an idea. Lowering the CEP using GPS is also technically possible - even if also expensive.


Very interesting comment. My own view is that we could far more profitably spend money on reducing the W76 yield (maybe even down to 0.05 kilotons). Realistically, we know how to do that. Developing a re-entry body with terminal seeker is a huge undertaking abandoned by the US. They are looking at other types of hypersonic missiles now, but I feel that in a situation where we require such a strike, the assurance provided by a low-yield nuke is far preferable. For example, if we need to wipe out a biological weapon proliferation threat.

A warhead that can flatten a small base is the sort of thing I think suits the character of the delivery system and the contemplated uses.
Also, a question to the OP - what's your source for all this very informative, somewhat technical information?
Original post by BeastOfSyracuse
Thanks very much, I really appreciate that :smile:

I completely agree regarding normalisation of nukes, my own view is that the 0.3 kiloton yield used against a time-sensitive target would only be used in the most extreme circumstances where its use is designed to end a major biological or nuclear proliferation risk or to pre-empt an attack using nuclear or biological weapons. They would only be used in the sort of circumstances where the world could understand why we resorted to such extreme measures.

Regarding low-yield weapons, the W48 is most impressive. It has a 0.072 kiloton yield (72 tons HE equiv), and it's tiny. Imagine fitting a plutonium implosion physics package in this tiny artillery shell, and engineering it to tolerate the 10,000G forces of being blasted out of a cannon (pic below)



Damn, that's impressive. I must admit, I do find nukes in particular quite fascinating. Not even from an edgy "I love destruction" point of view, the engineering and physics involved is just impressive to me.
Its a waste of money, we need nuclear weapons as a deterrent, but we don't need state of the art weapon systems with nuclear weapons.

Spend that money elsewhere.
Original post by Supersaps
A thoughtful post from the OP. Minor critique is that it's a bit of a chunk to get through but worth the read.


Thanks indeed, much appreciated.

- Firstly, it's a massive escalation of the situation even with a low yield weapon.


My own feeling is that we would only use it in the most extreme situations relating to biological or nuclear proliferation threats or a pre-emptive strike to prevent a biological of nuclear threat.

This is a bit sci-fi ish, but looking ahead 40 years, imagine we discovered an adversary had developed some kind of Grey Goo or nanotechnology with extinction-level implications. I know it seems far-fetched, but the future is always more complex and crazier than previous generations expect or predict.

I don't advocate using these weapons lightly, simply that there are certain scenarios that are very low probability for which we should still plan.

Thirdly, even ISIS having a nuclear weapon is a very different scenario from it being enough of an immediate threat to the UK to justify a nuclear pre-emptive strike because you need a means of delivery.


This is why I mentioned that it was in a remote area and they were about to move it. If it was in central Africa and it was being put on a truck, it could easily end up in one of the ports of West Africa, into a shipping container and on to Europe.

As I said, the threshold to justify such a strike is extremely high. But I do think there are scenarios other than the old "Moscow Criterion" strike that the Trident debate should consider
Reply 19
Some interesting arguments.
I personally object to the use of the "spin-doctored phrase":
NUCLEAR DETERRENT.
It is Nuclear weapons, plain and simple

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