The Obama administration has begun examining whether it can make cuts to its nuclear-weapons stockpiles that go beyond those outlined in a recent treaty with Russia.
The classified review is not expected to be completed until late this year, but some Republicans already are worried that it will go too far. On Tuesday, 41 Republican senators warned President Obama in a letter not to make major changes in nuclear policy without consulting Congress.
Arms-control advocates say the United States is mired in Cold War-era thinking about nuclear deterrence and are pressing the administration to use the review to rethink U.S. nuclear requirements. They say the decisions will be a test of Mr. Obama's commitment nearly two years ago to put the world on a path toward eliminating nuclear weapons.
Mr. Obama ordered the nuclear review early last year with an aim of shrinking the nuclear arsenal, but the work, led by the Defense Department, began recently, according to a Pentagon spokeswoman, Lt. Col. April Cunningham.
The review will look at issues such as what targets the U.S. would have to hit with nuclear weapons in a worst-case scenario and what kind of weapons it would need to hit them. Rethinking the requirements could open the way to cuts.
In the letter to Mr. Obama, Republicans warned against any big reductions from those outlined in the New Strategic Arms Reduction Treaty (START), ratified by the Senate and the Russian Duma in recent months. The treaty limits each side to 1,550 deployed warheads - a level military officials have said meets the need of the current directives.
Sharp reductions in nuclear forces "would have important and as-yet unknown consequences for nuclear stability," the letter said.
The letter was circulated by Sen. Jon Kyl, Arizona Republican, a leading opponent of the New START when it was considered in the Senate. It makes clear that significant changes in nuclear policy without consulting Congress could affect consideration of a new treaty with Russia. The 41 lawmakers who signed it include several who supported New START and represent sufficient numbers to block any treaty.
There is no indication that the Obama administration is considering drastic cuts as a result of the review. But the study could shape talks it has proposed with Russia on weapons not covered by the New START.
The administration wants to focus on stored nuclear weapons and those intended for short-range delivery, known as tactical nuclear weapons. But negotiations with Russia also could lead to further reductions in deployed long-range nuclear weapons.
Administration officials say the review has just begun and that no decisions have been made. In a broader look at nuclear-weapons policy last year, called the nuclear-posture review, the administration stressed the need for maintaining a strong U.S. deterrent.
"The United States will continue to ensure that, in the calculations of any potential opponent, the perceived gains of attacking the United States or its allies and partners would be far outweighed by the unacceptable costs of the response," the document said.
Disarmament advocates who follow administration thinking on nuclear issues say the document is unlikely to lead quickly to sharp cuts.
"For better or worse, it's not in the cards," says Daryl Kimball, head of the Arms Control Association, which advocates nuclear disarmament.