Without the test-ban treaty, there are no legal constraints on nuclear testing by the nuclear powers. The report said that if those powers resumed tests, countries such as Iraq, North Korea and Iran, which are suspected of trying to develop nuclear weapons, would be likely to conduct tests of their own.
"A future no-CTBT world . . . could be a more dangerous world than today's for the United States and for others," the report warned.
The report is unlikely to spur a new drive by the Democrat-run Senate to ratify the CTBT. The treaty failed to gain the necessary 67 votes - a two-thirds majority - in October 1999, when the 100-seat chamber was under Republican control.
Most Democrats support the test-ban treaty, but they would have to win more Senate seats to hold a new ratification vote.
Although opposed to the Comprehensive Test Ban Treaty, President Bush has said he has no plans to end a decade-old U.S. moratorium on underground nuclear testing. Vice President Cheney and Defense Secretary Donald H. Rumsfeld have argued that only periodic test explosions can ensure that U.S. warheads remain defect-free.
Some administration officials have urged the White House to revoke President Bill Clinton's signature on the treaty, to kill any chance of a new ratification vote.
Arms-control advocates and some lawmakers fear that the administration is slowly moving to resume testing. Among other things, they point to an administration proposal to slash the time necessary to stage a nuclear test.
The study was conducted at the request of retired Gen. John Shalikashvili, former chairman of the Joint Chiefs of Staff, who served as special adviser to Clinton on the nuclear test-ban treaty.
The National Academy of Sciences committee was asked to analyze the main technical concerns raised by opponents during the 1999 Senate debate. Those concerns are cited by Bush administration officials as arguments against a new ratification vote.
Administration officials and many nuclear-weapons experts say that as they age, U.S. nuclear warheads may develop defects that could affect their safety and performance. They insist that the only way to fully guard against such defects is to periodically remove a warhead from the arsenal and detonate it underground.
The academy's study noted that none of the 1,030 U.S. nuclear tests conducted between 1945 and 1992 was meant to detect age-related defects in stockpiled warheads.
It endorsed continuation of the Stockpile Stewardship Program, a multibillion-dollar effort that uses advanced experiments, non-nuclear tests, and ultra-high-speed computers to monitor the aging of weapons and simulate nuclear blasts.
Contact Jonathan S. Landay at 202-383-6012 or email@example.com.