The determination of Britain's political elite to maintain the country as a nuclear-weapons state is rooted in a half-century of military planning to which the possibility of tactical and first use of nuclear weapons is central.

In just five words, Gordon Brown, the United Kingdom's chancellor of the exchequer and would-be successor to Tony Blair, has intentionally reignited the debate over the future of Britain's nuclear weapons. In a wide-ranging speech on 21 June 2006 focusing on global markets, financial services and economic policy, he included as part of his prognosis for UK security in the 21st century the commitment to "retaining our independent nuclear deterrent".

As so often with New Labour, the way the entire speech was "spun" by Brown's aides was revealing. This element was, they indicated, key among all the topics the chancellor covered. As Andrew Rawnsley commented:

"It has enraged the left of the Labour Party. It was contrived to do just that. It was unashamedly designed – Mr Brown's acolytes make no pretence otherwise – to try to make the Chancellor a more appealing figure to Middle England" (see "Why Gordon Brown decided it was the time to go nuclear", Observer, 25 June 2006).

In the coming weeks and months there may well be a debate on plans to replace Trident – Britain's submarine-carrying ballistic nuclear-weapons system – and it is probable that Labour will, in due course, make its decision. There could be some discussion in parliament and there might even be a vote, though few doubt the outcome. "Middle England" will no doubt remain comforted by Britain preserving its civilised, semi-great-power status by retaining the capacity to kill tens of millions of people.

The wider point, though, is that there is a vigorous attempt to confine the debate to the limited theme of a "deterrent". Indeed, the entire debate is constructed along the very narrow premise that Britain's nuclear weapons offer, and have always offered, nothing more than a last-ditch deterrent protection against a would-be enemy threatening the country with annihilation.

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During the forty-five-year cold war, that enemy was seen to be the Soviet Union. This now presents some difficulties in that the much-missed "evil empire" has disappeared, removing the original point of possessing the bomb. It isn't clear, for example, how Trident could have prevented the London bombings of 7 July 2005. After all, nuking the home towns of the young bombers – Leeds and Dewsbury – in retaliation would have been a bit excessive, even for New Labour.

Still, George W Bush has neatly constructed an "axis of evil" to replace the late, lamented Soviet Union. This offers his closest ally Tony Blair (and his successor as British prime minister) the opportunity to argue that Trident's successor is designed to deter threats from those Islamofascists in Tehran, the world-conquering James Bond-hating hordes of North Korea, the Taliban when they take over Pakistan, the Naxalites when New Delhi finally falls and, of course, that historic enemy – the French.

Every part of this construct, however, is still underpinned by the doctrine of "deterrence". Middle England must rest secure in the knowledge that our nuclear weapons are "good" nuclear weapons and would only ever be used as weapons of final response – after, perhaps, not just Middle England but also the furthest bits of Wales, Scotland and even Northern Ireland had been turned to radioactive dust.

The problem with this is that it is one of the great myths of the nuclear age. Ever since the atom bombs on Hiroshima and Nagasaki performed the same destructive tasks that had previously required thousand-bomber raids (such as the devastating fire-bombing of Tokyo), the nuclear age has been replete with the idea that nuclear weapons are usable as weapons of war. This has been central to the North Atlantic Treaty Organisation (Nato's) nuclear planning, as well as to the Warsaw Pact (and now Russia).

Nato as an alliance, and Britain as a state, have long planned to fight nuclear wars at levels falling far short of a cataclysmic central nuclear exchange. This also means that Nato and Britain have had, and still maintain, policies that can envisage "first use" of nuclear weapons.

On the eve of what could possibly be a period of open debate about the role of Britain's nuclear weapons, it might be useful to trace this somewhat hidden history. This could serve the purpose of revealing matters that successive governments prefer to avoid discussing in public, and thus help ensure a more interesting debate.

This debate must consider two distinct issues: Nato as an alliance of which Britain is a prominent member, and Britain's long-term pursuit of policies for nuclear first use outside the Nato area.

The early days

Britain commenced its nuclear-weapons programme shortly after the end of the second world war. It tested a fission (atomic) bomb in October 1952 and a crude fusion (hydrogen) bomb in May 1957. By the end of the 1950s Britain had developed a strategic nuclear force based on the V-bomber medium-range jet bombers: the Valiant, Victor and Vulcan.

From the mid-1960s, Britain began to develop a force of ballistic-missile submarines capable of deploying the United States's Polaris submarine-launched ballistic missile (SLBM). The first such submarine, Resolution, started to patrol in June 1968, and control of the UK strategic nuclear force passed to the Royal Navy in July 1969.

Britain also developed a range of tactical nuclear weapons, principally bombs, deployed on a number of land-based and carrier-based strike aircraft from the late-1950s onwards. These included the Scimitar, Buccaneer, Jaguar and Sea Harrier, and the Lynx and Sea King helicopters. In addition, US-made nuclear depth-bombs were carried by Nimrod maritime-patrol aircraft; and Lance missiles and self-propelled artillery carrying US-made nuclear warheads were deployed with the British army in West Germany.

At its peak, in the early 1980s, Britain deployed some 400 of its own nuclear weapons together with several scores of US nuclear weapons. With the ending of the cold war, most of the types of nuclear weapons declined fairly rapidly, but two major types of British nuclear weapon remained in service until the late 1990s: the Polaris submarine-launched ballistic missile and the WE-177 tactical nuclear bomb.

In the 1990s, these were replaced by Trident, another submarine-launched missile. This is deployed with two warheads, a powerful strategic warhead many times more destructive than the Hiroshima bomb, and a "sub-strategic" or tactical warhead that has around half the explosive power of the Hiroshima bomb.

Since the 1950s onwards, Britain has operated a twin-track policy of committing nuclear forces to Nato and having them available for independent deployment and possible use.

Nato's nuclear planning

Although the early nuclear weapons of the 1940s and early 1950s were essentially strategic – intended for use against the core assets of an opposing state – the development of nuclear weapons intended for tactical use within particular war-zones was an early feature of the east-west nuclear confrontation. By the late 1950s, both the United States and the Soviet Union were developing relatively low-yield freefall bombs as well as early forms of nuclear-capable artillery. Over the next twenty-five years, a remarkable array of tactical nuclear weapons was developed and deployed, covering almost every type of military posture.

As well as freefall bombs, short-range battlefield missiles were developed along with nuclear-tipped anti-aircraft missiles and several types of nuclear artillery and mortars. Nuclear landmines known as atomic demolition munitions were developed that could be emplaced to destroy major bridges or tunnels or even block mountain passes. At sea, submarines were equipped with nuclear-tipped torpedoes, surface ships carried anti-submarine nuclear depth-bombs which could be delivered by missile or helicopter, and aircraft carriers could fly off strike aircraft carrying several kinds of nuclear bomb. There were even air-to-air missiles such as the US Genie, that were nuclear-armed.

By the 1980s, there were around 20,000 tactical nuclear weapons deployed by the United States and the Soviet Union, based in more than fifteen countries and on warships and submarines throughout the world. In the great majority of cases, the presumption was that if such weapons were used, they would not necessarily involve an escalation to an all-out nuclear war. In other words, nuclear war-fighting could be controlled. In Europe, perhaps the tensest region of the cold-war nuclear confrontation, both alliances had policies of the first use of nuclear weapons in response to conventional attack. (For a full discussion, see the relevant chapter, "Learning from the Cold War", in Paul Rogers, Losing Control: Global Security in the 21st Century, Pluto Press, 2002).

For Nato in the 1950s – before the Soviet Union had developed a large arsenal of nuclear weapons, the posture was codified in a military document MC14/2, colloquially termed the "tripwire" posture. Any Soviet attack against Nato would be met with a massive nuclear retaliation, including the use of US strategic nuclear forces; this assumed that the US could destroy the Soviet Union's nuclear forces and its wider military potential without suffering unacceptable damage itself.

By the early 1960s, the Soviet Union was developing many classes of tactical and strategic nuclear weapons, making it less vulnerable to a US nuclear attack. In such circumstances, MC14/2 became far less acceptable to western military planners, who consequently sought to develop a more flexible nuclear posture for Nato. This became known as "flexible response". It involved the ability to respond to Soviet military actions with a wide range of military forces, but also with the provision that nuclear weapons could be used first in such a way as to force the Soviet Union to halt any aggression and withdraw. Once again, it embodied the belief that a nuclear war could be fought and won.

The new flexible-response doctrine was progressively accepted by Nato member-states in 1967 and 1968. It was codified in a document entitled Overall Strategic Concept for the Defence of the NATO Area, or MC14/3. It was a posture with one particular advantage for the United States: that it might avoid nuclear weapons being used against its own territory.

A US army colonel expressed this rather candidly at the time, writing that the strategy:

"recognizes the need for a capability to cope with situations short of general nuclear war and undertakes to maintain a forward posture designed to keep such situations as far away from the United States as possible" (see Walter Beinke, "Flexible Response in Perspective", Military Review, November 1968).

Flexible response was to remain in operation for most of the last quarter century of the cold war, including periods of considerable tension in the early 1980s. Operational plans for nuclear use were (and are) developed by the nuclear activities branch of the Supreme Headquarters Allied Powers Europe (Shape) near Mons in Belgium, operating in conjunction with the US joint strategic target planning staff responsible for the SIOP strategic nuclear posture from its base in Omaha, Nebraska.

By the early 1970s, flexible response was well established under Nato's nuclear operations plan which embraced two levels of the use of tactical nuclear weapons against Soviet forces: selective options and general response. Selective options involved a variety of plans, many of them assuming first use of nuclear weapons against Warsaw Pact conventional forces. At the smallest level, these could include up to five small air-burst nuclear detonations intended as warning shots to demonstrate Nato's intent.

At a rather higher level of use were the so-called pre-packaged options involving up to 100 nuclear weapons. The US army field manual at the time defined such a package as:

"a group of nuclear weapons of specific yields for use in a specific area and within a limited time to support a specific tactical goal ... Each package must contain nuclear weapons sufficient to alter the tactical situation decisively and to accomplish the mission" (see Operations: FM 100-5, US Department of the Army, 1982).

While these different levels of selective use were thought to be possible ways of winning a nuclear war, the possibility remained that this would fail, and a more general nuclear exchange would result. This was the second level of use of tactical nuclear weapons; it was termed a general nuclear response in which Nato nuclear forces in Europe would be used on a massive scale along with US strategic forces.

Thus, by the end of the 1970s, Nato had developed a flexible-response strategy that involved detailed planning for the selective first use of nuclear weapons in the belief that a limited nuclear war could be won. By the early 1980s, with highly accurate fast ballistic missiles such as the Pershing 2 being deployed by the United States, there were indications that Nato was even moving to a policy of early first use of nuclear weapons.

One indication of this came in a remarkably candid interview given by the Nato supreme commander, General Bernard W Rogers. He said that his orders were:

"Before you lose the cohesiveness of the alliance – that is, before you are subject to (conventional Soviet military) penetration on a fairly broad scale – you will request, not you may, but you will request the use of nuclear weapons...[emphasis in the original]." (International Defense Review, February 1986).

The long-standing Nato policy of the first use of nuclear weapons was not promoted widely in public, where all the emphasis was placed on nuclear weapons as an ultimate deterrent. Even so, the policy was made clear on relatively rare occasions. One example is evidence from the UK's ministry of defence to a parliamentary select committee in 1988:

"The fundamental objective of maintaining the capability for selective sub-strategic use of theatre weapons is political – to demonstrate in advance that NATO has the capability and will to use nuclear weapons in a deliberate, politically-controlled way with the objective of restoring deterrence by inducing the aggressor to terminate his aggression and withdraw."

With the ending of the cold war and the collapse of the Soviet Union in 1989-91, there was some easing of Nato nuclear policy. This included the withdrawal of a substantial proportion of Nato nuclear weapons from western Europe as the Soviet Union withdrew from its former satellites in east-central Europe. The possibility of first use was considered increasingly unlikely, but not abandoned as a facet of Nato policy.

Although the Soviet Union is no more, Nato nuclear planning still involves a policy of first use, British nuclear weapons remain committed to Nato and the United States still maintains tactical nuclear bombs at one of its remaining bases in the UK, Lakenheath in Suffolk, eastern England.

Britain's independent targeting

Since the 1950s, Britain has deployed nuclear weapons on many occasions outside the immediate Nato area of western and southern Europe and the north Atlantic. This included the basing of RAF nuclear-capable strike aircraft in Cyprus in the 1960s and 1970s, regular detachments of V-bombers to RAF Tengah in Singapore in the mid-1960s, and the deployment of Scimitar and Buccaneer nuclear-capable strike aircraft on the Royal Navy's aircraft carriers from 1962 to 1978. Nuclear weapons were also carried on four task-force ships during the Falklands/Malvinas war of 1982.

This long history of "out-of-area" deployments of nuclear weapons by Britain is matched by a number of indications of a willingness to use them in limited conflicts. In one of the few published studies of British tactical nuclear targeting, Milan Rai wrote in his 1994 paper Tactical Trident (Drava Papers):

"Sir John Slessor, Marshall of the RAF in the 1950s, and one of the most influential military theorists of the period, believed that 'In most of the possible theatres of limited war … it must be accepted that it is at least improbable that we would be able to meet a major communist offensive in one of these areas without resorting to tactical nuclear weapons'."

This statement was made by a senior military figure rather than a politician, but similar comments did come from more official government sources. In 1955, the then defence minister (and later prime minister) Harold Macmillan stated in the house of commons:

"…the power of interdiction upon invading columns by nuclear weapons gives a new aspect altogether to strategy, both in the Middle East and the Far East. It affords a breathing space, an interval, a short but perhaps vital opportunity for the assembly, during the battle for air supremacy, of larger conventional forces than can normally be stationed in those areas."

Such an idea of a small nuclear war was further expressed during the 1957 defence debate by Macmillan's successor as defence minister, Duncan Sandys:

"one must distinguish between major global war, involving a head-on clash between the great Powers, and minor conflicts which can be localised and which do not bring the great Powers into direct collision. Limited and localised acts of aggression, for example, by a satellite Communist State could, no doubt, be resisted with conventional arms, or, at worst, with tactical nuclear weapons, the use of which could be confined to the battle area."

A tranche of British government letters, held in the national archives and released on 29 June 2006, provides further documentary evidence of this willingness to use nuclear weapons in the very period Macmillan and Sandys were speaking. One letter from defence minister Harold Wilkinson in 1961 refers to a possible Chinese attack on Hong Kong (then a British colony), and says: "Our object is to encourage the Chinese to believe than an attack on Hong Kong would involve US nuclear retaliation."

This historical context raises the question as to whether the smaller sub-strategic Trident warheads, or indeed the more powerful strategic versions, might be used independently of Nato. Britain reserves this right, and one of the more detailed assessments of the range of options for sub-strategic Trident warheads was made in the authoritative military journal International Defence Review in 1994:

"At what might be called the 'upper end' of the usage spectrum, they could be used in a conflict involving large-scale forces (including British ground and air forces), such as the 1990-91 Gulf War, to reply to an enemy nuclear strike. Secondly, they could be used in a similar setting, but to reply to enemy use of weapons of mass destruction, such as bacteriological or chemical weapons, for which the British possess no like-for-like retaliatory capability. Thirdly, they could be used in a demonstrative role: i.e. aimed at a non-critical uninhabited area, with the message that if the country concerned continued on its present course of action, nuclear weapons would be aimed at a high-priority target. Finally, there is the punitive role, where a country has committed an act, despite specific warnings that to do so would incur a nuclear strike (see David Miller, "Britain Ponders Single Warhead Option", International Defence Review, September 1994).

It is worth noting that three of the four circumstances envisaged involve the first use of nuclear weapons by Britain.

Such issues rarely surface in the public arena, but concern has been expressed in parliament that the government has not been sufficiently clear about the circumstances under which British nuclear weapons would be used in post-cold-war circumstances. For example, the house of commons defence select committee noted in 1998:

"We regret that there has been no restatement of nuclear policy since the speech of the then Secretary of State in 1993; the SDR [Strategic Defence Review] does not provide a new statement of the government's nuclear deterrent posture in the present strategic situation within which the sub-strategic role of Trident could be clarified. We recommend the clarification of both the UK's strategic and sub-strategic policy."

This was, in part, in response to comments made to the committee by the then secretary of state for defence, George (now Lord) Robertson. He had told the committee that the sub-strategic option was "an option available that is other than guaranteed to lead to a full scale nuclear exchange". He envisaged that a nuclear-armed country might wish to "...use a sub-strategic weapon, making it clear that it is sub-strategic in order to show that ... if the attack continues [the country] would then go to the full strategic strike," and that this would give a chance to "stop the escalation on the lower point of the ladder".

This statement indicated that "a country", such as Britain, could consider using nuclear weapons without initiating an all-out nuclear war, and that the government therefore appeared to accept the view that a limited nuclear war could be fought and won. It was evidently not the clear statement that the committee sought, and it did not indicate the circumstances in which such weapons might be used. In particular, it did not appear to relate to whether Britain or British forces had already been attacked with nuclear weapons, or whether nuclear weapons would be used first in response to other circumstances.

In addition to his weekly openDemocracy column, Paul Rogers writes an international security monthly briefing for the Oxford Research Group; for details, click here

A collection of Paul Rogers's Oxford Research Group briefings, Iraq and the War on Terror: Twelve Months of Insurgency, 2004-05 is published by IB Tauris
(October 2005)

The Iraq wars

At the same time, there had been no evidence to suggest that Britain had moved away from the nuclear posture of the cold-war era that included the possibility of using nuclear weapons first. Indeed, just as the cold war was winding down, the first Iraq war in early 1991 was one occasion when British nuclear use might have been considered. As the UK forces embarked for the Gulf in September 1990, the Observer reported that Britain was prepared to retaliate to an Iraqi chemical attack with nuclear weapons:

"A senior officer attached to Britain's 7th Armoured Brigade, which began to leave for the Gulf yesterday, claims that if UK forces are attacked with chemical gas by Iraqi troops, they will retaliate with battlefield nuclear weapons. The Ministry of Defence refused to confirm this last night, but it is the first unofficial indication that British troops might be authorised to use nuclear weapons to defend themselves if attacked" (see Observer, 30 September 1990, front page).

More than a decade later and prior to the start of the second Iraq war in 2003, the then secretary of state for defence, Geoff Hoon, was questioned by members of the select committee and appeared to indicate that Britain maintained this policy. In relation to a state such as Iraq he said: "They can be absolutely confident that in the right conditions we would be willing to use our nuclear weapons."

This exchange did not make clear whether this would be in response to a nuclear attack initiated by a state such as Iraq. Hoon was questioned on this point on 24 March 2002 on the Jonathan Dimbleby programme on ITV. He was asked whether nuclear use might be in response to non-nuclear weapons such as chemical or biological weapons. He replied:

"Let me make it clear the long-standing British government policy that if our forces or our people were threatened by weapons of mass destruction we would reserve the right to use appropriate proportionate responses which might ... might in extreme circumstances include the use of nuclear weapons."

Later in the exchange, Hoon made it clear that he could envisage circumstances in which British nuclear weapons were used in response to chemical or biological weapons. He was later asked by Dimbleby: "But you would only use Britain's weapon of mass destruction after an attack by Saddam Hussein using weapons of mass destruction?"

Hoon replied: "Clearly if there were strong evidence of an imminent attack if we knew that an attack was about to occur and we could use our weapons to protect against it."

The implication of this is clear – that there are circumstances where Britain would consider using nuclear weapons in response to a non-nuclear attack involving chemical or biological weapons and would even consider using nuclear weapons to pre-empt such an attack.

A time for air

Britain has deployed nuclear forces for almost fifty years. For most of that time, they have been primarily committed to Nato, which has maintained a nuclear-targeting posture that includes the first use of nuclear weapons. Britain also retains the capability to use nuclear weapons independently.

Although the publicly acknowledged "declaratory" policy remains one of "last resort" use of nuclear weapons, the "deployment" policy involves the idea of nuclear war-fighting that falls far short of responding to a nuclear attack on Britain. This is the long-standing reality. It could certainly liven up the forthcoming debate on replacing Trident if this enduring feature of British nuclear-weapons policy got a really thorough airing.