Ministers have signalled their commitment to the next generation of nuclear-armed submarines which promise to safeguard thousands of Westcountry jobs.
Defence Secretary Philip Hammond will today announce an extra £350 million in funding for the next stage of design work on the vessels that will replace the four ageing Vanguard-class submarines which currently carry Trident missiles.
The plans have major implications for Plymouth. Devonport is the UK's only base with the specialist facilities and skilled workforce needed to maintain the current and future submarine fleet.
The Vanguard submarines will be replaced from 2028 by the new vessels which are currently being designed by British firms. As a result of the latest funding, Babcock, which owns Devonport Dockyard, will go ahead with an additional £38 million worth of work. It follows on from £350 million in design contracts announced earlier this year, of which Babcock netted £15 million.
The move is like to put a further strain on the coalition as the Tories' Lib Dem partners are currently undertaking a review looking at whether there are cheaper alternatives to building the new missile-carrying vessels.
The Ministry of Defence has also revealed that one of the Vanguard submarines, HMS Vigilant, successfully fired an unarmed Trident ballistic missile during a test launch in the Atlantic Ocean last week.
Defence Secretary Philip Hammond said: "Our continuous submarine-based nuclear deterrent is the ultimate safeguard of our national security and the Government is committed to maintaining it, both now and in the future. The test firing and further investment in replacing the deterrent demonstrates that commitment.
"This latest expenditure for the next generation of nuclear-armed submarines is an investment in UK security and the British economy, sustaining high-quality jobs and vital skills."
First Sea Lord Admiral Sir Mark Stanhope said: "The Royal Navy has for over 43 years continuously operated the UK's nuclear deterrent to stringent safety standards and HMS Vigilant's latest test firing before she returns to the patrol cycle reflects that successful deterrence is based upon strong determination.
Mr Hammond also warned the Scottish Government that its policy of independence would hit jobs that depended on the Faslane-based deterrent, and the extra employment generated by relocating all submarines there by 2017.