US unveiling new, more restrictive nuclear policy

The Obama administration will narrow the circumstances under which the U.S. would use nuclear weapons, altering a decades-old policy that helped maintain the global balance of power during the tense days of the Cold War.

The administration plans to lay out the new policy Tuesday in a document called a nuclear posture review, drafted after a year of deliberation led by the Pentagon in consultation with allied governments.

The move, which seems certain to provoke a partisan debate, is just one in a series of White House initiatives limiting the role of atomic warheads in national defense, following President Barack Obama's pledge last year to move toward a nuclear-free world.

Secretary of Defense Robert Gates and Secretary of State Hillary Rodham Clinton were to discuss details of the new policy at a noon Pentagon briefing.

The document is expected to alter the role of nuclear weapons in defense policy by reducing the number of potential U.S. nuclear targets.

The new policy comes just two days before Obama and Russian President Dmitry Medvedev are scheduled to sign a new START treaty, a bilateral agreement that will cut the number of strategic warheads and missiles maintained by the world's two largest nuclear powers.

The White House's nuclear initiatives are intended to encourage other nations to reduce their stockpiles of atomic weapons or forgo developing them.

The U.S. officials said the administration's new policy would stop short of declaring that the United States would never be the first to launch a nuclear attack, as many arms control advocates had recommended. But it would describe the weapons' "sole purpose" as "primarily" or "fundamentally" to deter or respond to a nuclear attack.

That wording would all but rule out the use of such weapons to respond to an attack by conventional, biological or chemical weapons. Previous U.S. policy was more ambiguous.

The review of nuclear weapons policy is the first since 2001 and only the third since the end of the Cold War two decades ago.

Obama would commit not to use nuclear weapons against non-nuclear states that are in compliance with the Nuclear Nonproliferation Treaty, even if they attacked the United States with biological or chemical weapons. Those threats, he told The New York Times in an interview, could be deterred with "a series of graded options" - a combination of old and newly designed conventional weapons.

The White House also plans to urge Russia to begin talks on adopting first-ever limits on shorter-range, tactical nuclear weapons, an arena in which Russia holds an advantage, said the officials, who spoke on condition of anonymity because they were not authorized to discuss details of the policy review prior to its release.

Moscow has shown little interest in cutting short-range nuclear arsenals, because the Russian military relies on tactical weapons to balance what it sees as a threat from NATO to the west and China to the east.

On Tuesday, Foreign Minister Sergey Lavrov said Russia shares Obama's goal of a nuclear-free world, but said other nations must join the disarmament process as well.

Lavrov also said Russia reserves the right to withdraw from the new START treaty if it decides a U.S. missile defense shield, now planned for Romania, threatens its security.

U.N. Secretary-General Ban Ki-moon, in Kazakhstan Tuesday visiting a former Soviet nuclear testing range, called the new U.S. nuclear policy "an important initiative."

Obama is hosting dozens of world leaders in a nuclear security summit in Washington next week.

-- Associated Press writers Vladimir Isachenkov reported from Moscow, and Jim Heintz from Kazakhstan. (Copyright 2010 by The Associated Press. All Rights Reserved.)