"Our shipbuilding industry and our deterrent have never been more vital. We’ve committed to this programme and now we must press on," Fallon told the House of Commons on Wednesday.
He added that it was not wise to assume that nuclear threat would disappear in the next 30 years.
"Today I appeal to all moderate MPs, to put our national security first and to support building four new Trident submarines," Fallon stressed adding that the cost of building the submarines "is around three times the budget of the London Olympics."
The renewal of the costly Trident program was one of the top issues in the run-up to this year’s UK general election that propelled the Conservative Party, led by Prime Minister David Cameron, to a second term.
Earlier this month, Cameron suggested that Britain could consider using nuclear weapons in certain circumstances, keeping the ultimate insurance policy of an independent nuclear deterrent. His remarks came after a statement by new opposition leader Jeremy Corbyn, who stated that UK Tridents should never be used, even under an attack.
The Trident system, deployed at the UK Royal Navy’s Faslane, Scotland, naval base, is the UK’s only facility capable of hosting the four Vanguard-class Trident ballistic missile-equipped submarines.