A U.S. weapons expert says the Obama administration could pledge never to attack a nonnuclear state with nuclear weapons, provided that they were loyal upholders of the Nuclear Nonproliferation Treaty (NPT).

Quoting executive director of the Washington-based Arms Control Association Daryl Kimball, the British daily The Times said the U.S. could declare a "negative security assurance" to that effect.

He added, however, that proliferators North Korea and Iran would be excluded from such a pledge.

Kimball’s projection comes as the results of Obama's review of the U.S. policy on nuclear weapons are about to be released.

The newspaper said Obama is expected to reject George Bush’s doctrine on nuclear weapons that included the possibility of the U.S. launching an attack on a nonnuclear state.

The paper said Obama and the Defense Department have completed consultations on the matter and that the conclusions will be published early next week before Obama signs the new Strategic Arms Reduction Treaty (Start) with President Dmitriy Medvedev of Russia on April eighth.