Ministers have been warned by MPs that the skills base for building a new generation of nuclear submarines in the UK is at a "critical level".
Trident will reach the end of its scheduled life in 2024
The Commons defence select committee said the shortage of engineers was a "cause of serious concern".
Tony Blair has outlined plans - currently being consulted on - to spend up to £20bn on a new generation of submarines for Trident missiles.
Defence officials said they would study the MPs' recommendations carefully.
Committee members said the UK must work to keep its "world-class" skilled workforce.
They added that any future decisions must be based on the "strategic defence needs of the country, not on industrial and employment factors".
Replacing the current Vanguard submarine would be a "huge undertaking" and require a "uniquely skilled and specialist workforce".
Committee chairman Conservative James Arbuthnot said: "If we are to build a new generation of Trident submarines here in the UK, as the government's white paper suggests, we will have to work to sustain our manufacturing and skills base.
"The skilled workforce we have at Barrow, Devonport, Derby and Aldermaston are truly world class.
"If we lose them, we will lose our capability to design and build nuclear submarines."
A number of Labour MPs oppose the government's plan, but the Tories say it would be "crazy" not to have UK nuclear weapons. The Lib Dems want a decision put back to 2014.
The lifespan of the current Trident system is set to end in 2024 and ministers have said a decision is needed now to ensure the replacement is ready by then.
Critics believe the estimated £10-25bn cost would be better spent elsewhere and that Trident belongs in the Cold War era, not a time of threats to the UK such as international terrorism.
The Ministry of Defence said the committee's report would "provide a useful contribution to the forthcoming debate and vote in the House of Commons".
Defence procurement minister Lord Drayson told a meeting of the committee that it was "important that we ensure we have confidence" in the supply of submarines.
It was necessary to encourage scientists to have careers in the defence industry "so that we get greater expertise in the technology", he added.