U.S. President Barack Obama said Monday that he would substantially narrow the conditions under which the United States would use nuclear weapons, promising explicitly for the first time his country would not use nuclear weapons on non-nuclear states that are in compliance with the Nuclear Non-Proliferation Treaty (NPT).

Obama made the commitment in an interview with the New York Times on the eve of unveiling his administration's long-delayed Nuclear Posture Review.

He said countries that have violated or renounced the NPT, such as Iran and the Democratic People's Republic of Korea, would be considered "outliers," and not included in his promise.

The announcement eliminates the calculated ambiguity in U.S. nuclear posture since the beginning of the Cold War, and for the first time promised explicitly not to use nuclear weapons against non-nuclear states that are in compliance with the NPT, even if they attack the United States with biological or chemical weapons, or with crippling cyber warfare.

However, the paper quoted administration officials as saying the new strategy would still leave open the possibility of reconsidering the use of nuclear retaliation against biological attack, should such threat escalates to the level that makes the United States vulnerable to a crippling attack.

The Obama administration is set to release the Nuclear Posture Review Tuesday. The document establishes U.S. nuclear policy, strategy, capabilities and force posture for the next five to ten years.

White House spokesman Robert Gibbs said the new document will build momentum before the Global Nuclear Security Summit to be held on April 12-13 in Washington D.C.. The document is to be followed by a new disarmament treaty signing between the United States and Russia on Thursday. The two countries, who between them have 96 percent of the world's nuclear weapons, would slash their deployed nuclear weapons by a third.

It will be only the third such review to date, the previous ones issued by the Bill Clinton and George W. Bush administrations.

Analysts have been expecting a major change in the Obama administration's nuclear strategy from the previous Bush administration, which adopted a largely hawkish policy on nuclear issues and emphasized on both offensive and defensive nuclear capabilities.

Obama has sought to reduce the number and role of nuclear weapons in defense policy, with the ultimate goal of ridding the world of nuclear weapons, which he proposed in a Prague speech in April 2009.

One of the most controversial issue in the new document will be under which circumstances the U.S. reserves the rights to use nuclear weapons and whether the U.S. will make a no-first-use declaration, as some progressives had hoped.

Another issue will be the vexed subject of extended deterrence, sometimes referred to as the nuclear umbrella. Through military alliances, Washington has agreed to extend its nuclear umbrella over its allies and friends.

Under Obama's concept of a world without nuclear weapons, whether the United States should strengthen or reduce its extended deterrence has drawn a huge debate among experts and officials.