Although the United States signed the treaty on Sept. 24, 1996, the Senate considered the treaty in 1999 but narrowly rejected ratification in a debate that was too short and politicized. Since then, Congress has been missing in action and the Bush administration has publicly stated that it rejects ratifying the same treaty our nation already signed onto. This is despite a commitment by the United States at the 2000 Nonproliferation Treaty Review Conference to pursue the early entry into force of the CTBT.

Of the 44 nations that must ratify the Comprehensive Test Ban Treaty for it to enter into force, all but 10 have done so. Our allies and other original nuclear powers -- including France, Russia and the United Kingdom - have ratified the treaty, leaving the United States in the company of countries such as Iran and North Korea that have failed to ratify.

The United States' lack of leadership on this vital issue dooms one of the single-most important tools at our disposal to curb the proliferation of weapons of mass destruction.

At a time when we are facing threats from nations such as North Korea and Iran, and attempting to convince others such as India and Pakistan to become responsible nuclear powers, it is vital that America reclaims the leadership we once had on arms control.

The CTBT is still on the Senate calendar and available for consideration. If the Senate maintains its silence on this landmark anniversary, we will take another step further away from a recognized international goal, and leave ourselves vulnerable to a new global nuclear arms race.

At the time of the original debate, advocates for testing claimed that live nuclear testing was vital to maintaining the United States' nuclear arsenal and that the science-based stockpile stewardship program being used to ensure the safety and reliability of our arsenal without live testing would be inadequate. They were wrong then, and their arguments have only further eroded over time.

An exhaustive study by the National Academy of Sciences in 2002 found that for an aging nuclear stockpile such as ours, "nuclear testing is not needed to discover problems and is not likely needed to address them." The report also rejected the flawed argument that a science-based stockpile stewardship program would not keep up with an aging stockpile that was not subjected to periodic tests, noting that "we see no reason that the capabilities of those mechanisms - surveillance techniques, diagnostics, analytical and computation tools, science-based understanding, remanufacturing capabilities - cannot grow at least as fast as the challenge they must meet." In the Bay Area, we see first-hand at Lawrence Livermore Lab the dedication of scientists committed to ensuring our nuclear weapons remain a credible deterrent without opening the Pandora's box of live testing.

The Bush administration has shown a stark lack on leadership on this issue. It has repeatedly dismissed the CTBT and failed to encourage Congress to take the necessary steps for, at the very a least, a new look at this old tool. The American people deserve the security that the CTBT can deliver, not leaders in the White House or the Senate who would rather pass the buck than assume tough, responsible leadership. That's why I am introducing legislation calling on the Senate to immediately ratify the Comprehensive Test Ban Treaty.