In 2007, the UK Parliament began the process of developing a successor to the country's Trident-armed fleet of Vanguard-class submarines, which would allow the UK to maintain an unbroken deterrent patrol beyond the 100th anniversary of its becoming a nuclear-weapons state. At the insistence of the Liberal Democrat Party, however, the Cabinet Office has conducted a review of alternatives to this programme. Malcolm Chalmers explores the financial, strategic and technical issues raised by the review and analyses the vulnerabilities that the programme faces. He suggests that the UK remains committed to maintaining a nuclear deterrent with global reach, capable of confronting large as well as small nuclear powers into the indefinite future.