Mr Obama outlined his vision of a world free of nuclear weapons last April
US President Barack Obama is planning "dramatic reductions" in the country's nuclear arsenal, a senior US administration official has said.
This would come as part of a sweeping policy review designed to prevent the spread of atomic weapons, he said.
He added that the new strategy will point to a greater role for conventional weapons.
Mr Obama was holding a meeting with his Defence Secretary Robert Gates to discuss the new nuclear strategy.
The review "will point to dramatic reductions in the stockpile, while maintaining a strong and reliable deterrent through the investments that have been made in the budget," the official said.
He said the review would go further than previous reviews in "embracing the aims of non-proliferation. "
Officials say thousands of nuclear weapons could be cut, in many cases by retiring weapons that are now kept in storage.
The new strategy will also seek to abandon plans put in place by the previous administration to develop a new generation of nuclear weapons for penetrating underground targets known as "bunker busters."
The officials say the strategy will be an important step towards Mr Obama's declared aim of reversing the spread of nuclear weapons and seeking a world without them.
Last April, Mr Obama outlined his vision of a world free of nuclear weapons in a major speech in the Czech capital Prague.
He spoke of putting an end to Cold War thinking, a process in which, he insisted, the US was morally obliged to play a leading role.
He called for the forging of new partnerships to prevent the spread of nuclear weapons and a global summit on nuclear security, which will take place next month.
Ahead of the summit, the Obama administration began a wide-ranging nuclear policy review, which was initially supposed to have been released in December.
The BBC's Jonathan Marcus says all the signs are that the first draft of the document has been rejected as being too wedded to the status quo and not sufficiently "transformational" to use the language favoured by the Obama administration.
He says the review will be read closely to see what it might say about the potential circumstances in which nuclear weapons would be used, an issue Mr Obama is to discuss with Mr Gates.
The review comes as the US and Russia appear close to a new deal to cut their nuclear arsenals, despite Moscow's concerns over Washington's missile defence plans.
On Monday, Russian President Dmitry Medvedev said negotiations with the US on a replacement for the 1991 Strategic Arms Reduction Treaty (Start), which expired last December, had reached the stage of agreeing the nuances of the text.
"We are close to agreement on virtually all issues," Mr Medvedev said, but admitted that it was "not an easy subject".
The document will also set the tone for the next five-yearly review conference of the Nuclear Non-Proliferation Treaty, or NPT agreement, to be held in May.
The Obama administration is hoping to bolster the NPT, amid growing concern over Iranian and North Korean nuclear programmes.
Jonathan Marcus says Mr Obama will want to prevent the weakening NPT regime from unravelling, and to do so he needs to have powerful evidence that the US is taking its disarmament responsibilities seriously.
STRATEGIC NUCLEAR WARHEADS AROUND THE WORLD
All numbers are estimates because exact numbers are top secret.
Strategic nuclear warheads are designed to target cities, missile locations and military headquarters as part of a strategic plan.
Israeli authorities have never confirmed or denied the country has nuclear weapons.
The highly secretive state claims it has nuclear weapons, but there is no information in the public domain that proves this.
The International Atomic Energy Agency reported in 2003 there had been covert nuclear activity to make fissile material and continues to monitor Tehran's nuclear programme.
US officials have claimed it is covertly seeking nuclear weapons.