Tony Blair has secretly decided that Britain will build a new generation of nuclear deterrent to replace the ageing Trident submarine fleet at a cost of more than £10bn - a move certain to dismay thousands of Labour Party loyalists in the approach to polling day.
The disclosure that the decision has already been taken will expose Mr Blair - who has struggled throughout the election campaign to fend off accusations that he lied over the Iraq war - to fresh allegations of deception. He said last week that the decision would be taken after 5 May.
But The Independent has learnt that he has already decided to give the go ahead for a replacement for Trident to stop Britain surrendering its status as a nuclear power when the Trident fleet is decommissioned. The choice over the type of nuclear missile system that Britain will deploy is yet to be made. One Labour candidate described the new deterrent as "Blair's weapons of mass destruction".
The revelation comes as the United Nations hosts a five-yearly review of the nuclear non-proliferation treaty, to which Britain is a signatory. The five nuclear powers in the treaty promise to work towards global nuclear disarmament. Mr Blair will therefore face accusations of hypocrisy, for pressing other states, such as Iran and North Korea, to renounce their suspect nuclear weapons programmes while planning a new British deterrent.
The Independent can also reveal that Britain is involved in a plan to build a uranium enrichment facility in the New Mexico desert, with British Nuclear Fuels involved in a consortium to develop a $1.2bn (£630m) plant. The UN's nuclear watchdog wants a five-year moratorium on such facilities.
Critics argue that the twin developments make it more difficult for Britain to take a principled stance against states accused of building nuclear weapons in breach of the treaty. Fuelling those concerns, the White House said yesterday that it believed North Korea had test-fired a short-range missile into the Sea of Japan.
A senior defence source said: "The decision [to replace Trident] has been taken in principle very recently. US law does not allow the US to build bombs for us. We have to build our own."
Although Trident is not due to be decommissioned until 2024, "there is a very long lead time," the source said. "That is why the decision in principle had to be taken now."
Aldermaston, Britain's nuclear bomb-making facility, has been hiring physicists and mathematicians for the past year to retain the capability to build a new nuclear weapon when a new system is agreed. The source explained: "If you looked at the scientific press over the past year you would have seen an increase in advertisements for everything. It's mostly physicists and mathematicians, but it's a sign we are gearing up."
A small group of ministers including Geoff Hoon, the Secretary of State for Defence, is understood to be involved. Mr Hoon recently began studying papers on the options for a replacement.
Defence experts said the replacement for Trident would still be based on submarines, which are less vulnerable to counter measures. New submarines could be built in British yards, saving thousands of jobs. Britain could buy the missiles "off the shelf" from the US. The front-runner is a new generation of cruise missiles, based on the RAF's air-launched weapon, Storm Shadow, with its range increased.
But nuclear non-proliferation agreements forbid Britain from exchanging nuclear technology with the US, and so they would have to be equipped with British-made nuclear warheads. Britain supplies its own weapons-grade plutonium from the nuclear power plant at Sellafield.
Mr Blair hinted at the decision when he said on BBC Newsnight last week: "We have got to retain our nuclear deterrent. That decision is for another time. But I believe that is the right thing."
Both the Liberal Democrats and the Tories support the retention of a nuclear deterrent, but Mr Blair will face a battle with his own party. Rows over the British nuclear deterrent split the Labour Party in the 1980s and made it unelectable, until Mr Blair took over as leader and finally ditched any lingering support for the Campaign for Nuclear Disarmament.
But since the end of the Cold War in 1989 and the 11 September 2001 terrorist attacks in the US, the nature of the threat has dramatically changed. Many Labour members believe Britain faces a greater threat from terrorists with a "dirty" nuclear bomb than a rogue state firing sophisticated nuclear weapons.
Trident is virtually useless against such a terrorist threat, because the enemy does not present a target. The US is converting some of its Trident missile submarines to fire conventional cruise missiles, armed with tactical warheads, instead of the unwieldy ballistic nuclear missiles.
The US is also developing a new range of nuclear bombs, including smaller devices that could be used on the battlefield. This is controversial because it could lower the threshold for using nuclear weapons.
Clare Short, the former cabinet minister, said before the general election campaign began that she was "astonished" by the "quietness" of the party on the issue. "This will wake up the party," she said.
"It's just a symbol saying that Britain is in the big league, but if you need nuclear weapons to be in the big league, it's no wonder India and others want them. But when is Britain ever going to use a nuclear weapon when the US isn't? I would favour Britain becoming a leader in getting the non-proliferation treaty updated and back on course rather than going along with American breaches of it."
Tam Dalyell, the former father of the Commons, who is not standing at the election, said: "If Blair was wrong about Iraq, why should we trust him with updating Trident?"
Alan Simpson, a leading member of the left-wing Campaign Group, said: "These are Tony's weapons of mass destruction. Hans Blix, the UN weapons inspector could have looked no further than Downing Street before identifying the threat to international stability.
"There will be widespread resentment about this decision, taken in secret. This amounts to a £10bn first strike against better state pensions, school building and hospitals. If we build a new bomb, how can we tell Iran or North Korea they are wrong to do the same?"
Labour left-wingers are also gearing up to oppose the basing of America's national defence system in Britain, and any plans to site US missiles on British soil, which some claim would breach non-proliferation treaties.
Replacing Trident is one of several issues the Government has been keen to keep out of the political spotlight during the election campaign. Others are pensions, council tax and nuclear power, all of which have been kicked into the political long grass after reviews were ordered.
How successive governments have kept up in the global arms race
Does Britain need nuclear bombs of its own? There is a chasm between those who say "yes" and those who say "no". For much of the past 50 years, the UK's independent nuclear deterrent has been controversial. But every government since the last war has deemed it necessary.
Under the 1945 Labour administration of Clement Attlee, crucial decisions were taken about Britain's first atom bomb, which was eventually exploded in the desolate Monte Bello islands off Australia on 3 October 1952. Britain thus became the third member of the nuclear club, following the United States (1945) and the Soviet Union (1949).
A new generation of bombers to carry the threat was developed, the V-bombers - the Valiant, the Victor and the Vulcan - and when Britain stepped up a level in the club and developed the much more powerful hydrogen bomb, it was a Valiant that dropped the first British H-bomb on Christmas Island in the Pacific, in May 1957.
The attack technique switched to using "stand-off" bombs - early cruise missiles which could be launched 100 miles from the target. One short-lived version of that was the Blue Steel missile.
Britain had counted on buying a US missile to do it, Skybolt. In 1962 the US cancelled Skybolt, thereby hoping, many thought, to deprive the UK of its independent capability. British strategic defence policy was suddenly in tatters. The Prime Minister, Harold Macmillan, appealed to John F Kennedy to think again. After a walk with Kennedy he succeeded - astonishingly - in persuading the Americans to make available to Britain the submarine-based missile Polaris, on which they were basing their offensive capability.
The first British Polaris submarine went on patrol in 1968, an event signalling two changes that are still in effect to this day - the UK "independent" deterrent began to be operated by the Royal Navy, instead of the RAF, and became directly dependent on the Americans.
In the mid-1970s, under Labour governments, Polaris was secretly updated with a British multiple warhead, codenamed Chevaline. When it became obsolete, in the 1980s, the Thatcher government persuaded the Americans to share their submarine missile technology and sell the UK a replacement system, Trident.
The first of four giant British Trident missile submarines, HMS Vanguard, went on patrol in 1994. These four boats are each equipped with 16 American Trident missiles, with multiple warheads capable of vaporising targets more than 4,000 miles away. At least one is always on patrol.
But at some time in the coming 20 years, Trident will go the way of Polaris - ministers are thinking about its replacement.
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