In a speech to the movers and shakers in London's City financial district, Mr Brown let it be known that he was in favour of spending billions of pounds on a new generation of weapons to keep Britain in the global nuclear club.
"In an insecure world we must and will always have the strength to take all necessary long-term decisions for stability and security," said Mr Brown, who is almost certain to succeed Prime Minister Tony Blair as leader of the ruling Labour Party.
Britain, said Mr Brown in a speech that dwelled mainly on economic stability, would remain "strong in defence, in fighting terrorism, upholding NATO, supporting our armed forces at home and abroad -- and retaining our independent nuclear deterrent".
Political analysts said the almost passing remark signalled to the nation and the world that Mr Brown was committed in the long term to Britain remaining a nuclear power in the decades to come.
Britain's current nuclear deterrent was put into place in the 1980s by then prime minister Margaret Thatcher, when the Soviet Union - not global terrorist groups such as Al-Qaeda - was seen as the primary threat.
Tridents replacement
It is based on four Royal Navy submarines fitted with US-built Trident missiles which are due to become obsolete in the 2020s.
One of the submarines is always on patrol but the missiles are no longer pre-targeted.
Replacing the deterrent is likely to cost anywhere from 10 billion to 25 billion pounds ($A25 billion to $A62 billion), observers say.
Mr Blair reiterated in parliament earlier that there would be a "fullest possible debate" on Trident's future, although he refused to commit himself to a decisive vote in parliament on the issue.
Some 122 members of parliament, including 93 Labour deputies, have signed a parliamentary motion urging Mr Blair's government to allow them a vote on the issue.
Critics say that by keeping its deterrent, Britain would be flaunting a commitment under the global nuclear Non-Proliferation Treaty to move to nuclear disarmament.
They also point out that nuclear missiles are near-useless in fighting terrorist cells.
Lord Garden, who as Air Marshall Timothy Garden was a former assistant chief of defence staff, said the government was wrong to think it must make a decision on Trident's future in the coming years or months.
He told BBC television: "We have great uncertainty in the world. It may be that the world will get safer and we won't need a nuclear weapons system. It may be that the world will get more dangerous, and we will."
The chairwoman of the Campaign for Nuclear Disarmament, Kate Hudson, said that if the deterrent was renewed, it would "only contribute to global tensions and lead other countries to conclude that they also need to develop nuclear weapons".
Liam Fox, the defence spokesman of the main opposition Conservative Party, dismissed Mr Brown's remarks as "just more spin" designed to cast Mr Blair's heir apparent as a "statesman".
Mr Blair, whose Labour Party is suffering its lowest ratings in public opinion polls in two decades, is widely expected to step down as prime minister some time during the current parliamentary term, making way for Brown.