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 is to meet his Defence Secretary Robert Gates later on Monday 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.
New partnerships
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.
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.
