Following a deal with Russian President Vladimir Putin to reduce nuclear stockpiles, the Bush administration is preparing to destroy thousands of warheads under its strategic nuclear plan.

The administration's Nuclear Posture Review does not estimate the total number of warheads to be de-activated, but it does call for more spending to prepare for future underground nuclear bomb tests, should they be needed.

Last November, after meeting with Russian President Vladimir Putin, Bush pledged to cut the U.S. long-range nuclear arsenal by two-thirds, to between 1,700 and 2,200 warheads. The new strategic nuclear plan reflects those numbers, said congressional sources briefed on the plan Tuesday.

Underground nuclear weapons testing is currently banned under a 1992 moratorium, but it would take three to five years to resume testing at Nevada's test site if the United States were faced with the need.

The administration has no plans to resume testing of nuclear stockpiles, said White House press secretary Ari Fleischer, but it has not been ruled out.

"We never rule out the possible need to test, to make certain that the stockpile, particularly as it's reduced, is reliable and safe. So, he has not ruled out testing in the future, but there are no plans to do so," he said.

On Tuesday, Defense Secretary Donald H. Rumsfeld said the administration is committed to the ban on underground tests. "It certainly doesn't recommend resuming testing," Rumsfeld said when asked about the Nuclear Posture Review.

But concern over testing by defense officials and some congressional members arises out of a recognition that the country's nuclear warheads are aging and may not be able to work as expected if they were ever used.

The Energy Department and nuclear weapons labs are responsible for the nuclear stockpiles and are in the process of finding alternative ways to test the performance capabilities of weapons without actually detonating any through computer simulations, but the technology is still a few years off. In the meantime, they want to certify that the reduced stockpile will work.

The recommendations of the Nuclear Posture review has test ban supporters and non-proliferation advocates crying foul against the administration.

The review is "part of a pattern that they want to move toward nuclear testing," said John Isaacs, president of the Council for a Livable World.

"This is a surprisingly modest effort" to revamp the nation's strategic nuclear plan "given that President Bush ...had promised a fundamental rethinking of our nuclear weapons posture," said Ivo Daalder, a nuclear arms specialist at the Brookings Institution.

Despite the anger, several internal audits by the Energy Department's inspector general raised concern about the department's current programs for finding flaws and defects in warheads. Investigators found backlogs of as much as 18 months in testing, inspections and monitoring.

"If these delays continue the department may not be in a position to unconditionally certify the aging nuclear weapons stockpile," wrote DOE Inspector General Gregory Friedman.

The Associated Press contributed to this report.