By Jack David
The Wall Street Journal
February 21, 2009

It's back. A decade after its rejection by the Senate, the Comprehensive Test Ban Treaty (CTBT) is once again under consideration. President Barack Obama says he wants the Senate to ratify it "at the earliest, practical date." But to what end? As the ratification debate of the 1990s showed and the last 10 years confirm, the CTBT is irrelevant to the world's main nuclear dangers and may actually encourage the very proliferation it aims to stem.

In 1992, the U.S. unilaterally pledged to forgo all nuclear testing involving a "critical" explosion, i.e., an explosion of fissile material involving a self-sustaining chain reaction. In 1996, the U.S. voted for the CTBT when it was adopted by the U.N. General Assembly and the U.S. became the first country to sign it. In 1997, President Bill Clinton sent it to the Senate. In 1999 the Senate denied approval, 19 votes short of the 67 necessary.

The CTBT is a product of Cold War discussions about eliminating the testing, use and possession of nuclear weapons. By 1990, existing treaties already curtailed parties from testing above ground as well as underground where the yield of the nuclear test exceeds 150 kilotons. The CTBT goes further, binding parties not to "carry out any weapon test explosion or any other nuclear explosion."

U.S. ratification would have no legal consequences. The CTBT is not binding on any country until 180 days after all 44 countries named in Annex 2 have ratified it. Annex 2 countries include: India, North Korea and Pakistan, which have not even signed the treaty, and China, Egypt, Indonesia, Iran and Israel, which haven't ratified it. As recently as January, India's foreign minister, Pranab Mukherjee, said flatly: "India will not sign the CTBT."

In the hard-to-imagine event that all 44 Annex 2 countries sign and ratify the CTBT, the scope of its ban is not clear. Enforcement will be impeded by disagreement among countries about what constitutes compliance. It also will be impeded by the fact that some tests can be designed to evade detection.

Treaty proponents argue that U.S. ratification "would send a signal" to the rest of the world. But a signal of what? The U.S. already has stopped tests involving explosions with nuclear yields. It has dismantled more than 13,000 nuclear weapons since 1988, reduced its strategic nuclear weapons stockpile to 40% less than the Strategic Arms Reduction Treaty permits, and the U.S. vigorously supports virtually all existing nonproliferation regimes. Are we to believe that U.S. ratification of the CTBT will persuade, say, North Korea and Iran to respect a testing ban?

As a practical matter, by ratifying the CTBT the U.S. will impede its own potentially necessary testing even if it does not restrict action by any other country. Given that CTBT proponents argue that ratification will "send a message," there is little doubt that, upon ratification, the U.S. will honor its zero-yield standard and claim "credit" for abiding by the CTBT.

The safety and reliability of our nuclear arsenal is a major concern. In 1999, when the Senate rejected the CTBT, experts testified that parts of our nuclear weapons wear out, corrode or decay and are difficult to replace. A letter opposing ratification signed by six former secretaries of defense -- James Schlesinger, Frank Carlucci, Dick Cheney, Melvin Laird, Casper Weinberger and Donald Rumsfeld -- was submitted to the Senate. The letter stated that the computer simulations we now count on for assurance that our aging nuclear weapons and their parts are reliable and safe may one day be insufficient and actual testing may become necessary.

Moreover, dozens of our allies and partners depend upon U.S. nuclear weapons for their security. The letter from the six defense secretaries observed that if the U.S. were to ratify the CTBT, "confidence in the reliability of our nuclear weapons stockpile would inevitably decline, thereby reducing the credibility of America's nuclear deterrent." If this were to happen, they said, our allies and partners "could well feel compelled to seek nuclear capabilities of their own." The secretaries concluded that the CTBT is "incompatible with the nation's international commitments and vital security interests."

President Obama says he is committed to bringing about a safer world and a more secure United States. U.S. ratification of the CTBT will not advance those goals.

Mr. David was deputy assistant secretary of defense from September 2004 to September 2006.