The UK should scrap its nuclear arsenal, former defence secretary Michael Portillo has said.
A nuclear deterrent would be a waste of money, Mr Portillo says
He wrote in the Sunday Times that the existence of the Soviet Union had demanded a nuclear deterrent but "none of those considerations applies today".
"Aircraft carriers and submarines that fire cruise missiles" would be more "useful", Mr Portillo said.
Defence Secretary John Reid told ITV's Jonathan Dimbleby show the UK would keep "the minimum nuclear deterrent".
A government decision on replacing the Trident nuclear deterrent is due within three or four years.
Mr Portillo, who stood down from his Kensington and Chelsea seat at the last election, said: "Whatever residual risk may be posed by Russia's poorly managed nuclear arsenal can be handled by the United States.
"If the UK diverts billions of pounds from its future defence budgets into nuclear weapons that will never be used, it will have less money to spend on useful things such as aircraft carriers and submarines that fire cruise missiles."
He added: "We could be more powerful and a more useful ally for America if we did not waste money on renewing the nuclear deterrent."
Mr Reid told Jonathan Dimbleby that in the past five years "we have reduced the number of warheads, we have de-targeted the Trident boats, we've reduced the number of boats at sea on nuclear weapons, we got rid of our free-fall nuclear bombs".
But he added: "While others have nuclear weapons we have said we will retain the minimum nuclear deterrent."