Washington ? A prestigious Defense Department panel has recommended major changes to the United States’ nuclear arsenal, saying the current plans to refurbish the existing weapons stockpile will not protect the nation from new threats from rogue states and terrorist groups.

A task force of the Defense Science Board said it was “most urgent” to create strong defenses against these new threats. In a report distributed inside the Pentagon last month, it said U.S. strategic forces should emphasize smaller nuclear warheads and should arm the nation’s 50 giant Peacekeeper intercontinental ballistic missiles with conventional warheads to allow a wide variety of options for targeting hostile forces.

“The nuclear weapons program as currently conceived — a program focused primarily on refurbishing the (current) stockpile — will not meet the country’s future needs,” the DSB group said in its study, made public last week by Steven Aftergood of the Federation of American Scientists. “Nuclear weapons are needed that produce much lower collateral damage,” the panel said, indicating the need for greater precision, reduced radioactivity and the ability to dig deep into the ground to get hard targets.

The DSB recommendations come at a time when the Bush administration is struggling to determine the future size and makeup of the current U.S. nuclear stockpile of about 6,000 warheads, an issue that has been pending for more than two years. At a Senate Armed Services subcommittee meeting this past Tuesday, Energy Secretary Spencer Abraham said he hoped the plan, which was due to be sent to Congress last month, would be sent soon.