The Pentagon’s strategic review unveiled yesterday calls for a smaller nuclear force but one that will not compromise an effective deterrence against potential adversaries, according to a top DoD official.

Michele Flournoy, the undersecretary for defense policy, told reporters the Department of Defense will continue to upgrade the strategic nuclear fleet “as necessary” but maintained that deterrence will be possible with reduced forces.

“The strategy is very clear that we will continue to field a safe and secure and effective deterrent in that we will continue to modernize and recapitalize as necessary,” Flournoy said.

Flournoy did not detail the size of the reduction, saying that information will be available when the Pentagon goes public with its fiscal 2013 budget proposal later this month.

“It’s our judgment that we can maintain deterrence at lower levels of forces but I will defer any discussion as to specific programmatic details to the budget when it rolls out,” she said.

The strategic review, titled Sustaining U.S. Global Leadership: Priorities for 21st Century Defense, seeks to outline the Pentagon’s priorities for global operations in a reduced budget environment, as the department will have to absorb at least $480 billion in spending reductions over the next decade.

Rep. Mike Turner (R-Ohio), the chairman of the House Armed Services Committee’s strategic forces subpanel, promptly criticized the plan, saying the United States cannot reduce its nuclear deterrent at a time when China and Russia are modernizing their arsenals and with the looming threat of Iran’s and North Korea’s nuclear ambitions.

“The U.S. cannot be alone in disarming itself of nuclear weapons,” he said in a statement. “Reductions to our nuclear deterrent should only come as a result of proportionate cuts from our adversaries as well.”

“This review leaves both our nation and our allies unsure of the future of our nuclear deterrent, and our ability to counteract attacks from those who seek to do us harm,” he added.

It remained unclear whether the envisioned nuclear reductions will go beyond what is required in the New Strategic Arms Reduction Treaty (New START) with Russia. New START entered into force in February and calls on both countries to cut their deployed number of nuclear warheads to 1,550 by 2018.

It also remained unclear how smaller numbers would impact the “triad” of sea-, land- and air based systems for delivering nuclear weapons. There has been some talk in Washington of possibly eliminating one element of the triad, an option strongly objected to by senior military officers and numerous members of Congress.

Maj. Gen. William Chambers, assistant chief of staff for strategic deterrence and nuclear integration, said late last year that smaller numbers of warheads in the active arsenal makes it even more critical to keep all three delivery systems.

“As numbers decline, it becomes increasingly important to maintain a force structure and a force posture with diverse and complementary attributes,” Chambers said (Defense Daily, Nov. 1, 2011). Getting rid of one part of the triad would negatively affect the other two, he added.

Previous Pentagon budget documents outline spending $100 billion over the next 10 years on nuclear modernization. But that could be affected by the current fiscal situation.

The austerity measures come at a time when the Air Force weighs the development of its next generation of long-range, deep-strike bomber and the Navy is in the early stages of developing its next ballistic submarine to replace the current fleet of Ohio-class SSBNs. The Navy anticipates starting to retire the Ohio-class subs toward the end of the 2020s. Senior Air Force and Navy officials have identified the long-range strike program and Ohio-class replacement as top priorities.