Obama Narrows the Range of Possible Targets in New National Nuclear-Weapons Policy.

WASHINGTON—The Obama administration will release a new national nuclear-weapons strategy Tuesday that makes only modest changes to U.S. nuclear forces, leaving intact the longstanding U.S. threat to use nuclear weapons first, even against non-nuclear nations.

The Obama administration will release a new national nuclear-weapons strategy Tuesday that makes only modest changes to U.S. nuclear forces.

But the new policy will narrow potential U.S. nuclear targets, and for the first time makes explicit the goal of making deterrence of a nuclear strike the "sole objective" of U.S. nuclear weapons, a senior Obama administration official said Monday.

Also for the first time, nations complying with their nuclear non-proliferation obligations that attack the U.S. or its allies with chemical or biological weapons will no longer be threatened with nuclear retaliation, the official said. But the president will make clear they would "face the prospect of a devastating conventional attack," the official said.

The document, known as the Nuclear Posture Review, is the first rethinking of the U.S. nuclear strategy since President George W. Bush released his revised policies three months after the Sept. 11, 2001, attacks. It does offer clearer assurances that non-nuclear nations complying with nuclear proliferation accords will not be targeted, and it moves toward additional safeguards against accidental nuclear launches. But more dramatic changes, contemplated just weeks ago, were shelved after President Barack Obama secured a nuclear arms-control treaty with Russia that will shape the U.S. arsenal for the next decade.

Journal Community

The release of the review will kick off a lengthy series of defense-policy events that Mr. Obama hopes will further his aims of countering the proliferation of nuclear weapons and materials, and of isolating Iran.

On Thursday, he and Russian President Dmitry Medvedev will sign a treaty cutting deployed U.S. and Russian nuclear arsenals by 30%.

Meanwhile, Russian Foreign Minister Sergey Lavrov said Tuesday that Russia reserves the right to withdraw from its new arms-control treaty with the U.S. if it decides the planned U.S. missile-defense shield threatens its security, the Associated Press reported. Mr. Lavrov said Russia will issue a statement outlining the terms for such a withdrawal after Messrs. Obama and Medvedev sign the treaty, AP reported.

"Russia will have the right to opt out of the treaty if qualitative and quantitative parameters of the U.S. strategic missile defense begin to significantly effect the efficiency of Russian strategic nuclear forces," Mr. Lavrov told the AP.

Next week, more than 40 heads of state convene in Washington for a summit on counter-proliferation, which will lead to efforts at the United Nations to tighten economic sanctions against Iran to choke off its nuclear ambitions. Next month, Mr. Obama will try to use the first U.N. review of the Non-Proliferation Treaty in five years to toughen the treaty and isolate two of its scofflaws, Iran and North Korea.

"Release of nuclear posture review will set the stage," said a U.S. official involved in proliferation issues.

To many arms-control advocates, the review is likely to be a disappointment. "It's a status quo document, I think, in virtually every respect," said Bruce Blair, president of World Security Institute and co-coordinator of Global Zero, a disarmament group.

With Senate approval needed for the pact with Russia to cut nuclear arsenals, administration officials did not want to commit to dramatic changes in nuclear policy that opponents could use to build opposition to the treaty, Mr. Blair said. Republican Senate aides said they expected a document they could embrace.

But the administration official said the "adjustments" in the U.S. position narrow any contingencies for a nuclear strike. The document will say "there remains a narrow range of contingencies in which the option of using nuclear weapons can play a role in deterring large-scale conventional, chemical or biological attack," he said. But it will add that Washington "will continue to move" toward "making nuclear deterrence the sole objective" of the arsenal. The adjective "sole" has become a key measurement in diplomatic circles where U.S. nuclear forces have long been seen as an impediment to stopping nuclear proliferation.

The document will more clearly say the U.S. will not attack non-nuclear nations that have signed and are complying with the U.N. nonproliferation treaty, according to officials familiar with it. That effectively narrows the potential U.S. nuclear targets to the eight declared nuclear powers, as well as Iran and possibly Syria, said Joseph Cirincione, president of the Ploughshares Fund, an arms-control group. U.S. officials consider those two nations to be not fully compliant with the nonproliferation treaty.

The nuclear strategy will not take U.S. nuclear weapons off submarines, bombers and missiles that could fire them at a moment's notice. But the administration will recommend changes to the nuclear command structure that would make accidental launches more unlikely, officials said. They will also call for fortifying U.S. nuclear launch systems, so military officials would not believe they have to launch a nuclear strike out of fear that an incoming attack would destroy the U.S. response capacity.

For the first time, the strategy makes counter-proliferation the highest priority of nuclear policy makers.

The new strategy will emphasize reducing reliance on the role of nuclear weapons in deterrence, and will commit to accelerating the deployment of non-nuclear deterrent capabilities, such as missile defenses and the forward deployment of U.S. forces to trouble spots.

But the administration backed away from language that its allies in the arms-control community believed they would secure. Officials considered detailing their goals for the next round of arms talks with Russia, including controls on battlefield tactical nuclear weapons, dismantling mothballed warheads and reducing total deployments to 1,000 warheads a side, down from the 1,550 limit in the new treaty. But the new doctrine will not contain such specifics, nor will it adopt language threatening nuclear attack only against nuclear threats.

"The United States should be able to clearly state that the only purpose we hold nuclear weapons for is to deter the use of nuclear weapons," said Daryl Kimball, executive director of the Arms Control Association. "There is no conventional threat out there that we cannot counter with our overwhelming conventional forces."

—Jay Solomon contributed to this article.