Although such proposals may lead to financial savings, they are deeply flawed and could have far-reaching strategic and political implications for both the United Kingdom and its NATO allies. With Clegg now part of Prime Minister David Cameron's coalition government, he will hopefully "get real" about Trident, as former Prime Minister Gordon Brown urged in the second prime ministerial debate on April 22.

Rather than enhancing U.K. and NATO security, the arming of submarines with nuclear missiles during crises is potentially destabilizing, since it could provoke an adversary to increase their own state of readiness. By contrast, continuous at-sea deterrent patrols virtually eliminate the risk of sending inadvertent escalation signals. Even if the nuclear-armed submarines may never be called upon, they provide a hedge against unforeseen threats while minimizing the risk of crisis escalation. 

It is also debatable whether a system based on cruise missiles will provide an adequate deterrent. The range of a cruise missile is up to 1,550 miles, in comparison to a Trident D-5 ballistic missile, whose range is over 4350 miles. This means that in order for a submarine armed with cruise missiles to carry out an effective strike, it must be closer to its target, making it more susceptible to attack. Cruise missiles are also more likely to be shot down if detected. Given these factors, such a weapon system will only add limited value to NATO's defense posture. Furthermore, the merit of maintaining a nuclear weapons platform that only has limited deterrence capability should be heavily scrutinized.

The reduced range of cruise missiles would also make the U.K. more dependent on the U.S. extended deterrence. U.K. submarines carrying ballistic missiles have the ability to deliver an immediate and assured retaliatory strike. Without this capability, the United Kingdom may be compelled to rely on the United States, and its Article V obligations under the North Atlantic Treaty, in the event that an instantaneous response to an attack was required. Before scrapping the Trident replacement system, the British government will need to assess whether it is willing to accept a transformation of the nuclear relationship from one based on U.S. "assistance" to one more akin to U.K. "dependence."

But it's not just the transatlantic relationship that will be affected. The U.K. strategic deterrent is assigned to NATO and forms an integral part of the alliance's defense posture. Scrapping Trident will alarm allies in Eastern Europe, who may see it as a weakening of NATO's strategic deterrence -- particularly its European-based component. These concerns will make it more difficult to reach a consensus on withdrawing U.S. tactical nuclear weapons from Europe, as states that have regional security concerns -- such as Estonia, Poland and Turkey -- may view such a withdrawal as a step too far. Paradoxically, therefore, the end of the U.K.'s Trident system and its continued at-sea presence may have a negative impact on any U.S. attempt to reduce European-based tactical nuclear weapons.

There is also the issue of multilateral disarmament: Any decision to scale back Britain's nuclear deterrent will be seen by the international community as based purely on financial, as opposed to moral and political grounds, since the Liberal Democrats have based their argument on the need to rein in defense spending. This consideration, coupled with the fact that the Liberal Democrat proposal would not result in complete disarmament, means that London would not be seen as "leading by example," but rather as grappling to deal with the consequences of the financial crisis. Such a perception is unlikely to precipitate similar reductions in other nuclear weapons states' arsenals. 

Therefore, despite the expense, there is a strong argument to be made for moving ahead with the replacement of the Trident delivery platform, while at the same time re-emphasizing the United Kingdom's willingness to include its nuclear forces in any multilateral moves towards complete disarmament.

Although the United Kingdom has an overstretched defense budget that needs trimming, making savings by scaling back the nuclear deterrent is not the solution. Given that the Liberal Democrats are now part of the governing coalition, their position on nuclear issues is of greater importance, especially since the question of Trident renewal may yet be included in the upcoming Strategic Defense Review. If it is, then those involved must remember that the positive role that the country plays in advancing multilateral nuclear disarmament could be undermined if London appears motivated by financial savings alone. And while replacing the Trident system will be expensive, the Astute-class alternative may have unintended strategic costs that London and NATO simply cannot afford.

**Thomas Young is a research associate at the James Martin Center for Nonproliferation Studies in Monterey, California. His work has appeared in the Bulletin of the Atomic Scientists and on the Web site of the Nuclear Threat Initiative.