Trident and Nuclear Law by Rupert Ticehurst

1. Introduction:

On 15 December 1994, the United Nations General Assembly (UNGA) adopted resolution 49/75K agreeing to submit an advisory opinion to the International Court of Justice (ICJ) on the legal status of nuclear weapons. The request submitted to the ICJ sought an opinion on the following question: “Is the threat or use of nuclear weapons in any circumstance permitted under international law?”. On 8 July 1996, after considering oral and written evidence from a very large number of states, the ICJ released its advisory opinion.

This advisory opinion is undoubtedly one of the most important issues the Court has had to address. At stake was the credibility of international law and the credibility of the ICJ itself; furthermore, at issue was also the future survival of humanity. Not surprisingly, therefore, the Opinion has given rise to a considerable volume of writing . In addition, I organised a conference that took place at King’s College in London on 15 November in which many distinguished academics and practitioners from around the world participated. All of this has been very interesting. Much of what has been said and written has been extremely informative and often very clever. However, I feel that very little of it has been of use to assist those people concerned with the legal status of Trident Nuclear Missiles. This is because commentators have tended to concentrate on the wider issue of the legality of nuclear weapons in general, rather than concentrating on the legality of the use of specific types of weapon. That is what I propose to do in this paper.

2. The Unique qualities of nuclear weapons:

It is essential to place nuclear weapons within a scientific context, otherwise the legal issues become abstract. Evidence of the effects of nuclear weapons had been extensively documented by the WHO in two reports in 1984 and 1987.


However, it is impossible to be specific about the effects of nuclear weapons because they will vary depending the yield of the weapon used, the location, timing and height of blast and the prevailing weather conditions. Nevertheless, through the process of fission or fusion, nuclear weapons produce heat and blast considerably greater than any conventional weapon. In addition they release radiation which can affect health, agriculture, natural resources and demography over a very wide area exposing present and future generations to a very substantial risk of genetic defects and to a damaged environment, food and marine ecosystems.

The effects of heat and blast and, in particular, radiation cannot be controlled in space or time. For these reasons, nuclear weapons are unlike any conventional weapons. They are weapons of mass destruction affecting present and future generations.

3. The Opinion of the International Court of Justice:

i. The threat or use of nuclear weapons:

In giving its Opinion, the Court was not operating in a vacum: to an extent therefore international political reality informed the opinion of the Court. It is hard to imagine how the nuclear powers would have reacted to a opinion of absolute illegality: I think we can assume that such an opinion would not have been welcomed. In fact, it would probably have been ignored or discredited as would the reputation of the Court. Equally, the Court was aware of the expectations of other, mainly third world, states.

Placed in such a difficult position, it is disappointing but not altogether surprising that the Court did not confront head on the issue of legality in the now famous paragraph 105(2)E.

“It follows from the above-mentioned requirements that the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law;

However, in view of the current state of international law, and the elements of fact at its disposal, the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a state would be at stake.”

This represents a statement that comes very close to a ruling of absolute illegality but then introduces an escape clause regarding self-defence. The paragraph was decided by a vote of 7 to 7: the President having the casting vote in favour of paragraph 2E. However, the picture is more complicated than this. Each judge gave a separate opinion providing an interpretation of this paragraph and it is clear that not all judges voting in favour of 2E hold the same views as to the legality of nuclear weapons. Furthermore although 7 judges dissented, 3 of them dissented because they believed that international law prohibited nuclear weapons absolutely .

It is I think worth noting that the proponents of illegality had the odds very much stacked against them in this case. This is mainly because of the way international law operates. It depends on state consent either to a treaty or to the development of custom. Evidently the nuclear states and their allies have resisted the development of either in relation to a prohibition on nuclear weapons. The fact that the vast majority of states strongly oppose nuclear weapons and have condemned them in countless UNGA resolutions is not in itself enough to create a legal norm prohibiting nuclear weapons. The GA is not a law making body. Had it been possible to escape from this positivist legal structure, the anti-nuclear movement would undoubtedly have got the answer that it wanted. .

The case was therefore not decided on the basis of an absolute prohibition but on the general rules of humanitarian law and law of self-defence. The Court had to balance what are called the Hague and Geneva laws with New York law, so called because it is located in the Chapter vii of the UN Charter and is therefore governed by the UNSC. States have an inherent right to use military force in self-defence: this is enshrined in the UN Charter. However, the right of self-defence does not override humanitarian law . So it does not matter how just the use of force in self-defence, humanitarian law must always be observed.

However, many of the provisions of humanitarian law are flexible, such as the prohibition on unnecessary suffering: this does not prohibit suffering, it states that the suffering must not be more than is required to remove a combatant from the conflict. The issue therefore is whether in an extreme scenario of self defence the balance can shift sufficiently in favour of military necessity to justify the use of nuclear rather than conventional weapons. This is the issue that the Court could not resolve.

ii. Disarmament:

The Court’s opinion on disarmament was not solicited by the GA. Nevertheless, the Court gave its opinion on the obligation on nuclear states to dismantle their nuclear programs as found in Article VI of the Non-Proliferation Treaty. The Court stated unanimously in paragraph 2F that “There exists an obligation to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament…”. In the body of the Opinion, the Court stated that “the obligation involved here is an obligation to achieve a precise result – nuclear disarmament in all its aspects – by adopting a particular course of conduct, namely, the pursuit of negotiations on the matter in good faith”. This is an obligation which does not rest on the nuclear states alone: it is an obligation on all state parties to the Non-Proliferation Treaty.

Given the unanimous voting on paragraph 2E, this must be considered to be an authoritative interpretation of the treaty. Nuclear states are now required to achieve nuclear disarmament through good faith negotiation.

4. Trident:

i. Introduction:

The United Kingdom’s nuclear program is concentrated on Trident: a submarine launched ballistic missile system (SLBM). This replaces the Polaris system which has now been scrapped. The UK’s remaining nuclear program consists of WE-177 free falling bombs carried by RAF Tornado aircraft which are in the process of being scrapped. The short-range lance nuclear missiles and the nuclear artillery shells formerly based in West Germany have been scrapped as have the Royal Navy’s nuclear depth charges. US nuclear weapons have almost completely been withdrawn: what remains are B-61 free fall bombs stored at Lakenheath in Sussex.

The Trident program, when complete, will include 4 nuclear powered submarines, each carrying up to 16 Trident II D-5 missiles. These missiles can carry 8 100kt nuclear warheads each capable of striking different targets, although the UK system will probably have between 4-6 warheads per missile. Consequently, a Trident submarine can potentially hit 96 different targets, each with a weapons 8 times more powerful than the bomb dropped on Hiroshima which killed an estimated 130, 000 people. The number of warheads can be varied, consequently, the UK could deploy 1 missile holding only 1 warhead. Trident is more than a replacement of Polaris: it represents a considerable upgrade on that system.

Trident was designed to be a non-variable yield warhead; that is, the warhead yield will always be in the region of 100kt. There has been some reference from the MOD of a sub-strategic role for Trident. However, a sub-strategic role would require either replacing a 100kt warhead with a warhead of a lower yield (5-10kt) or making the existing non-variable yield warhead a variable yield warhead. There is absolutely no evidence that either has been achieved. In truth, we do not know for sure. However, it is assumed that no such warhead has been developed and that when the MOD talks of a sub-strategic role for Trident, they refer to using 1 warhead rather than multiple warheads. However, this still involves the use of a 100kt warhead which is evidently too powerful to fulfil a sub-strategic or tactical role. The UK always has at least one Trident submarine on patrol at any point in time. The Commander of the submarine may be ordered to fire missiles which he will be obliged to do: he will have no idea why the missiles are being deployed or what the intended target is.

ii. The ICJ decision and Trident:

It is important to note that the Opinion did not consider any specific nuclear program held by any nuclear state. The ICJ was asked to consider the legality of nuclear weapons in general. Therefore, for the Opinion to be of use to us, it is necessary to convert the general language of the Opinion and apply it to the specific context of the use of Trident by the United Kingdom. In achieving this, I will concentrate on 3 points: Trident and humanitarian law; Trident and New York law; Trident and disarmament law.

As expected, the United Kingdom considers that its nuclear program complies with the law as stated in the opinion. This is what I intend to discuss.

a. Trident and humanitarian law:

In paragraph 78 of the Opinion, the ICJ affirmed one of the most important principles of humanitarian law, namely that “States must never make civilians the object of attack and must consequently never use weapons that are incapable of distinguishing between civilian and military targets.”. It is important to notice that, in this statement, the Court is equating the use of an indiscriminate weapon with the targeting of civilians: in other words they amount to the same thing.

The issue that has to be resolved is whether Trident is capable of making this distinction between civilian and military targets. This is not a question of targeting, because Trident can be accurately targeted. It is a question of the explosive yield and radiation release of Trident.

The requirement to distinguish between civilian and military targets is different from the issue of collateral damage. The rules on collateral damage allow the use of a weapon that hits a military target but causes collateral damage to civilians and civilian targets, as long as that damage is justified by the necessity of destroying the military target. So, for example, it would be lawful to attack a strategically important military air base even if the attack damages civilian houses located near to the air base.

However, nuclear weapons of 100kt are so powerful that the target is inevitably very large. For these reasons, Trident falls foul of the requirement in humanitarian law to distinguish between civilian and military targets. To return to the air base scenario. A 100kt warhead cannot be targeted to destroy an air base: the weapon is simply too powerful for that target. The surrounding civilian targets rather than being collateral, are inevitably a part of the actual target. A 100kt warhead is therefore not able to make the distinction between civilian and military targets, and its use must therefore be unlawful regardless of the extremity of the scenario of self-defence involved.

Pro-nuclear lawyers work hard to invent scenarios where this is not the case i.e. where the military object is so big that it can be the target of a single weapon or alternatively where the military target is so far away from civilian targets that the military target can be hit without damage to civilian targets. These arguments are very difficult to respond to because the scenarios involved used are hypothetical: the whole Russian naval fleet advancing in the middle of the Atlantic closing in on British waters; the destruction of a nuclear submarine at great depth or under an arctic shelf with a nuclear depth charge. The latter is particularly puzzling since the UK no longer possess nuclear depth charges.

So the lawyers are busy making up problems to justify the retention of nuclear weapons. This process involves developing hypothetical scenarios in which hypothetical weapons may be used in hypothetical locations. Had the burden of proof in the nuclear weapons case been on the nuclear weapon states to prove the legality of nuclear weapons in the proceedings before the ICJ, the lawyers would have been forced to submit some real scenarios which they would then have found far more difficult to defend.

Even if successful in locating a real scenario, nuclear weapons emit radiation which will inevitably effect civilian targets wherever the weapon is used. This has to be taken into account when determining what the target of the weapons is. So if a 100kt nuclear weapon is detonated in a desert with the intention of destroying an air base, it may cause 10 miles of destruction which, if the air base is located 30 miles from the nearest civilian target, will not cause any immediate damage to civilian targets. However, the weapon will emit substantial radiation which will effect civilians over a very wide area. In this case, the issue is the extent of the target of the bomb: is it the air base, the 10 miles of devastated territory or the wider area affected by the radiation. In my opinion, the target must be the wider area which will inevitably be affected by the radiation.

A further and often overlooked point here is that the area affected by the bomb will be dangerous to civilians who may, in the future when the military conflict is long since finished, want to make use of the affected site. Not only can a nuclear bomb not be contained in space, it has an enduring affect which cannot be contained in time . For these reasons it is not possible for a large scale nuclear weapon to meet the requirement of distinguishing between military and non-military sites. Had the question submitted to the ICJ in fact been “due to the environmental and humanitarian consequences involved, would it ever possible to use a 100kt weapon lawfully”, the answer would certainly have been “no”.

In this assessment, I am in part seeking support from the separate statements of 2 judges who voted in favour of Paragraph 2E. Judge Fleischhauer stated that “the nuclear weapon is, in many ways, the negation of humanitarian considerations underlying the law applicable in armed conflict…the nuclear weapon cannot distinguish between civilian and military targets”. President Bedjaoui stated that “nuclear weapons seem to be – at least at present – of a nature to hit victims indiscriminately, confusing combatants and non-combatants…The nuclear weapon is a blind weapon, and therefore by its very nature undermines humanitarian law, the law of discernment in the use of weapons”. One wonders why these judges voted in favour of paragraph 2E. Given their views, it seems that they should have voted with the minority 3 judges supporting the position of absolute illegality.

When the capabilities of Trident are assessed in relation to the relevant humanitarian provisions, it is clear that it could not be used without violation of international law. Why, then, does the UK deploy Trident? Either because it is a political rather than a military weapon, in other words, it has no military function but nevertheless ensures that the UK remains a “big player”; or, the UK retains Trident on the pretence that it may in some inconceivable hypothetical example be lawful, knowing that, if forced, it will be used in a way which violates international law.

b. Trident and New York law:

As we have seen in paragraph 2E, the ICJ stated that it could not determine whether in an extreme scenario of self-defence when the very survival of a state was threatened, nuclear weapons could be lawfully used.

The first point to make here is that it cannot be concluded that the Court is implying that the use of nuclear weapons is lawful in these circumstances: it could not determine this point, neither did it give any indication of circumstances when the use of nuclear weapons might be lawful. It would be wrong therefore to state that the Opinion does not affect the UK nuclear program: it patently questions the whole legality of the program.

Interestingly, paragraph 97 which is in the substance of the Opinion differs in wording to paragraph 2E of the dispotif: “Accordingly, in view of the present state of international law viewed as a whole, as examined by the Court, and of the elements of fact at its disposal, the court is led to observe that it cannot reach a definitive conclusion as to the legality or illegality of the use of nuclear weapons by a state in an extreme circumstance of self-defence, in which its very survival would be at stake.”

This statement indicates that a state could only use nuclear weapons when its very survival is at stake. This rules out the use of nuclear weapons in collective self-defence; i.e. the use of nuclear weapons by one state to defend another state. To take real example, the invasion of Kuwait by Iraq in 1990 temporarily extinguished the State of Kuwait. Under these circumstances, other states were entitled to come to the aid of Kuwait. However, paragraph 97 indicates that, in the view of the Court, although Kuwait may have been able to use nuclear weapons if it was a nuclear weapon state, neither the US or the UK could use nuclear weapons in defence of Kuwait or its own soldiers because the very survival of neither state ever at stake.

This is extremely important, yet often overlooked. UK and NATO policy remains that nuclear weapons could be used in collective self-defence: I quote Baroness Symons, Parliamentary Under Secretary of State at the Foreign and Commonwealth Office, “the United Kingdom’s nuclear deterrence policy remains entirely defensive: we would only ever consider the use of nuclear weapons in extreme circumstances of self-defence, which includes defence of our NATO allies” . The legality of this policy is highly questionable.

Is the inclusion of the word “its” in paragraph 97 a mistake? That is possible because the word is not included in the dispotif. In any event I think it is wrong to approach the Opinion in the way a tax lawyer would approach tax legislation. It is equally important to look at the underlying message the ICJ is giving. The Court clearly felt that humanitarian law does not permit the use of nuclear weapons. However, it felt that in an extreme scenario of self-defence the balance of humanitarian law and military necessity may shift sufficiently in favour of military necessity to allow the use of nuclear rather than conventional weapons.

What is clear is that the Court is trying to limit the use of nuclear weapons to a very narrow situation: an extreme circumstance of self-defence. This is because of their extraordinary destructive capability and the inherent risk of escalation. Given this, it appears from the Opinion in its entirety that the Court is ruling out the use of nuclear weapons by the United Kingdom when a NATO ally is invaded by a non-NATO force. This is a very interesting position because it involves the creation of 2 levels of self-defence: individual and collective for which different rules apply.

Moving away from the point of collective self-defence, it is worth pointing out that it is ironic that none of the acknowledged nuclear states actually need nuclear weapons to ensure their survival. They are all strong enough to deter any aggression through conventional means and in the case of the US and UK function within regional military organisations to ensure their survival through conventional means.

Of course, a realistic extreme scenario of self-defence can be proposed: the invasion of Israel by a coalition of neighbouring states intent on the destruction of the state of Israel. History has shown us that this is not entirely implausible. I do not propose to deal with the issue of Israel because I wish to focus on the UK. I mention that scenario because it serves to demonstrate the implausibility of the need for the UK to possess nuclear weapons. Almost 1000 years of history has shown us that, as an Island, the UK is virtually impossible to invade. Therefore the very survival of the UK is not under threat and never would be.

Furthermore, in order to comply with the requirements of international humanitarian law it would be necessary to use a weapon of limited yield because, as I have argued above, high yield weapons will inevitably violate international law. There is in this proposition an inherent contradiction: in a situation where a state’s very survival is at stake, it can only use a nuclear weapon of limited yield in a remote locality or underwater which, because it is small and remote, would have very little effect in defending the aggression which it is assumed is of an overpowering nature. In that case, therefore, it would be unlawful.

c. Trident and disarmament law:

As we have seen above, The UK has streamlined its nuclear program and proposes to retain one system: Trident. This amounts to a 21% warhead reduction and a 59% reduction in explosive power. The previous Government therefore maintained that it is already complying with its obligation to disarm. However, the elimination of certain weapons is not the same as bringing to a conclusion negotiations leading to nuclear disarmament. As the UK has no intention of eliminating its Trident program, it is not in compliance with paragraph 105(2)E of the Opinion or article VI of the Nuclear Non-Proliferation Treaty. Furthermore, Trident is in fact a considerable development of the UK program in that it is able to hit more targets at much greater distances with greater chance of successful strike. What the UK has done is replace out of date technology with a much more effective system and dressed this up as disarmament. Statements by NATO, or individual states, that existing nuclear weapon policies will be maintained for the indefinite future is wholly inconsistent with the obligation to seek disarmament as is the further development, including testing, of nuclear weapons. We need look no further than the Queen’s Speech opening the first Parliament of this government, in which it was stated that it is the intention of Her Majesty’s Government to keep “strong armed forces including the nuclear deterrent.”. When setting out how the Government intended to conduct its Strategic Defence Review, George Robertson stated that “We will maintain strong conventional forces and our national nuclear deterrent. These are our bottom lines.”. In other words, the outcome of the defence review would result in the retention of Trident. This appears to be the same as the former-Conservative Government’s position as presented by Michael Portillo in the House of Commons: “The Government will maintain nuclear weapons because we need to maintain a deterrent that keeps this country safe”. The UK voted against the Malaysian proposed UNGA Resolution on the grounds of its unrealistic call for time-bound multilateral negotiations in paragraph 2. Yet there has been no proposal by the UK or other nuclear weapons states for a realistic timetable. The above clearly sets out the position of the UK in relation to Trident and that position is wholly inconsistent with its obligations under international law to disarm its nuclear program.

5 Conclusion:

It is not possible for me to say that the threat or use of Trident is unlawful. I am not a court of law so I am not in a position to determine this point. I can state that after an assessment of the ICJ Opinion, I believe that the threat or use of Trident is not compatible with international humanitarian law because of the high yield nature of the Trident warheads. Further, I am also of the opinion that the threat or use of Trident in collective self-defence is not permitted in international law: if lawful at all, nuclear weapons can only be used in an extreme scenario of individual self-defence. Finally, the ICJ confirmed that states must work towards disarming their nuclear programs. This is an obligation that has been placed on states since the NPT came into force. It is an obligation that has been consistently flouted by the nuclear states not least the UK when purchasing Trident to update the old Polaris system. At the very least, the UK must accept that the legality of its Trident program is brought into considerable doubt by the ICJ Opinion. Its continued deployment raises very important legal and military issues which must as a matter of urgency be addressed.


Rupert Ticehurst

Barrister, lecturer in law

School of Law,

King’s College


London WC2R 2LS

tel: 0171 836 5454 ext. 1269

fax: 0171 873 2465