The Future of Britain's Nuclear Deterrent

Politics, not strategy, might set the United Kingdom's course.

A perennial question faced by the major nuclear powers is how many and what kinds of nuclear forces are necessary to maintain an effective, credible deterrent. Contending assessments of security threats, as well as differing strategic concepts, have traditionally informed the debate. Yet, the tug-and-pull of domestic politics can also play a significant role in determining a nation’s nuclear policy.

That’s certainly the case in the United Kingdom today. A decision on the future of Britain’s nuclear deterrent could depend as much on the dynamics of intracoalition and interparty politics—and a referendum on Scottish independence—as it does on strategic analysis.

Missiles and Submarines

The United Kingdom is one of the five nuclear-weapon states officially recognized by the 1968 Nuclear Nonproliferation Treaty. At one time, it fielded a wide variety of nuclear-capable weapon systems. (According to Professor Sir Lawrence Freedman, these included longer-range bombers, fighter aircraft and maritime helicopters capable of delivering British-produced nuclear weapons; as well as short-range land-based missiles and artillery able to fire U.S. nuclear weapons under a dual-key arrangement.) But by the late 1990s, Britain had phased out all of its air-delivered and land-based nuclear-weapon systems as part of a post–Cold War adjustment that led to a substantial reduction in the total number of deployed nuclear weapons.

Today, the UK’s nuclear force consists of four Vanguard-class nuclear submarines, each armed with up to sixteen Trident D-5 ballistic missiles. The UK builds its own submarines and nuclear warheads; the missiles are purchased from the United States under the terms of a sales agreement that dates back a half-century. With four submarines in service, at least one can always be under way and on patrol. British government officials have long regarded “continuous at-sea deterrence” as essential to maintaining a credible deterrent, because it ensures that at least a portion of the nuclear force is likely to survive any attack and still be capable of mounting a retaliatory strike.

The UK will soon be forced to decide on a successor to the current Trident system. Its ballistic-missile submarines were built between 1986 and 1999, and are expected to reach the end of their service lives starting in the 2020s. Given the long lead times required to design, construct and commission new submarines, serious work will need to begin soon if they are in fact to be replaced.

Coalition Politics

A final decision on what to do as the UK’s Trident submarines age out has been purposely put off until 2016, after the next general election. Nevertheless, the positions of the major political parties are already well established. In 2006, Prime Minister Tony Blair’s Labour government decided to “maintain our deterrent system beyond the life of the Vanguards with a new generation of ballistic-missile-carrying submarines.” Conservative leaders—including current prime minister David Cameron—have similarly advocated “like-for-like” replacement of the existing UK ballistic-missile submarines.

The junior partners in the present ruling coalition—the Liberal Democrats—have taken a different view. They have for some time argued that like-for-like replacement of the current Trident boats would be inordinately expensive. Moreover, they maintain that a continuous at-sea deterrence posture—and thus a four-submarine fleet—is no longer necessary in the post–Cold War security environment.

After the May 2010 general election, the Conservatives and Liberal Democrats struck a compromise of sorts while forming their coalition. They agreed, inter alia, that the new government would remain committed to the maintenance of Britain's nuclear deterrent. (To this end, some initial work on replacing the Vanguard-class submarines has been undertaken and funded.) However, the coalition agreement also stated that “the renewal of Trident should be scrutinised to ensure value for money.” Additionally, the Liberal Democrats were explicitly allowed to continue making the case for alternatives.

Last week, the Cabinet Office released the long-awaited results of an internal review on likely alternatives. The written report examines the costs and strategic implications of various weapons systems, including stealthy or supersonic cruise missiles that could be launched from large aircraft, fast jets, surface ships, or attack submarines. It also addresses various “force postures,” ranging from the current practice of having a portion of the force always on full alert to more relaxed levels of readiness.