Below is outlined a range of arguments against continuing a UK nuclear weapons capacity and some responses to frequently used arguments in favour.

Moral, legal and social reasons against:

Nuclear weapons are immoral

History has shown that war is usually pragmatically inadvisable and at most only a short-term way of solving conflicts. Many also see it as immoral. The use of nuclear weapons is certainly immoral. On the criteria of the St. Thomas Aquinas Just War concept, it involves damage out of all proportion to the advantage gained, and does not discriminate between combatants and civilians. The nuclear bombs dropped on Hiroshima and Nagasaki (not to mention the conventional weapons used against German, Japanese and British cities) produced primarily civilian casualties. Nuclear weapons are indiscriminate not only in killing living individuals but also in affecting generations as yet unborn.

Nuclear weapons are illegal

In 1966 the International Court of Justice stated that the use of or threat to use nuclear weapons would be contrary to international law, with the possible exception of use in self-defence when the survival of the state was at stake. Their use is contrary also to the principles and rules of humanitarian law.

The renewal of our nuclear weapons would be in direct contravention of the Nuclear Non-Proliferation Treaty

In a statement issued by the Review Conference on this treaty in 2000, the five original nuclear weapon states gave an “unequivocal undertaking…. to accomplish the total elimination of their arsenal leading to nuclear disarmament…” However, the continuing possession of nuclear weapons by the original nuclear weapon states has encouraged other countries not to sign the treaty and even to acquire nuclear weapons themselves, thus leading to increased nuclear proliferation and another nuclear arms race. Conversely, the UK setting an example by discarding its weapons would encourage others to do likewise and lead the way to a non-nuclear world.

Misuse of the financial resources involved

The UK has so far spent £50 billion on its Trident ‘nuclear deterrent’. It has been calculated that this could buy 500 UK city hospitals, provide drinking water and sanitation for the entire developing world, or clear all the world's landmines.

Pragmatic reasons against:

A nuclear posture could give rise to fatal misunderstandings

So long as the UK possesses nuclear weapons, any nation facing a nuclear attack might suspect the UK and retaliate. This would not happen if we were known to have discontinued Trident.

Britain’s vulnerability to nuclear attack

The UK has very high population density and a complex infrastructure on which our civilization depends. If we discarded our nuclear weapons we would be very unlikely to be subject to nuclear attack, as there is an international understanding that nuclear weapons will not be used against non-nuclear states.

Vulnerability to Anti-Ballistic Missile systems

If the USA were successful in developing such a system, other nations might follow suit. Depending on the effectiveness of such systems, UK nuclear weapons would become ineffective.

There are better alternatives for ensuring our security

Very few countries have chosen to possess nuclear weapons, and some have decided to abandon them (South Africa, Libya, and some of the former Soviet republics). Alternatives include supporting the role of the United Nations and international law, the techniques of conflict resolution, and having stronger conventional forces.

A number of arguments are often advanced for continuing a UK nuclear weapon capacity. Below are responses to those arguments:

That UK nuclear weapons provide strategic defence of the UK by deterring a nuclear-capable adversary

Whether or not ‘deterrence’ was effective in the Cold War, the situation has now changed. Russia is extremely unlikely to quarrel with the UK specifically, and the probability of attack from any other nuclear weapon state is similarly remote: attack by one of the states that has recently acquired nuclear weapons would mean it was risking the total retaliatory destruction of that state. Thus ‘deterrence’ is no longer an acceptable justification for retaining nuclear capability.

That UK nuclear weapons could be used during war

There is a notion that the UK could, independently of NATO, use its nuclear weapons to defeat or threaten a less well-armed adversary. This has not happened in any of the wars in which the UK has been involved since 1945. It would require a decision that would override moral and legal scruples, and risk ostracism by other nations. Public opinion would be strongly against it.

That UK nuclear weapons provide a multiplicity of decision centres within NATO

The UK provides only 2.5% of the NATO nuclear capability, and a situation in which the UK would use its nuclear weapons alone is inconceivable. Thus it can have little influence on NATO decisions on the use of such weapons.

That UK nuclear weapons can be a counter to nuclear blackmail

A nuclear weapon state could threaten the UK and force major concessions without fear of nuclear reprisals. But there is no state that could plausibly act in this way, and the predictable consequences for any state that did would not be acceptable to it.

That nuclear capability gives us a place on the Security Council

Membership of the Security Council is not determined in this way, and the UK's nuclear capability has not so far given it a place in key disarmament negotiations, nor did it enable the UK to influence Pentagon thinking on Iraq.

That UK nuclear weapons are a bargaining counter in multilateral disarmament negotiations

It has not been used in this way so far. Conversely, our example of discarding nuclear weapons could provide an example to others.

Conclusion

Thus there are strong moral, legal, social and pragmatic arguments against the UK retaining nuclear weapon capability, and the arguments in favour of doing so are at best weak. Furthermore, the arguments for the possession of nuclear weapons by the UK would apply to any state, and would lead logically to the conclusion that every state should have them. Do we want a world governed by mutual threat rather than one governed by moral and legal considerations? Are we going to base our world on a culture of peace or a culture of violence?

(Based on an article by Christopher Watson)