In Washington, bad ideas never die. Exhibit A: the Comprehensive Test Ban Treaty (CTBT), which was rejected by the Senate twelve years ago.

With the controversial New START agreement already in its pocket, the Obama administration is now working to build support for the CTBT, which would outlaw all nuclear-explosive testing. It would be the next leg of the journey down the president’s fanciful “road to nuclear zero.” The Senate should not go along for the ride.

In talking up the CTBT, the administration offers a “moral leadership” argument: By forswearing nuclear testing, the U.S. will inspire other states to forgo nuclear weapons. The folly of that argument is even clearer today that when the Senate rejected it in 1999. We haven’t tested our nukes since 1992. (Yikes!) Since then, Pakistan, India, and even North Korea (originally a non-nuclear-weapons state under the Nonproliferation Treaty) have tested nuclear devices. Iran continues its nuclear-weapons program at full throttle, and all the other nuclear states are modernizing their arsenals. Russia and China, for example, are almost certainly conducting low-yield nuclear-weapons tests.

The biggest problem with the CTBT, however, is that eliminating the testing option makes it virtually impossible to maintain a safe, reliable, and militarily effective nuclear arsenal. Testing, after all, can provide crucial information about our nuclear-weapons stockpile, which has atrophied considerably since the end of the Cold War.

Ponder this: If your teenager had to make a vitally important trip, would you allow him to take a car that hadn’t been driven for over 30 years? Many of our nukes were built over 30 years ago, and they were designed to last only 20 years. And those weapons are far more sophisticated than an Olds Omega.

Defense Secretary Robert Gates acknowledged the problem three years ago, warning, “There is absolutely no way we can maintain a credible deterrent and reduce the number of weapons in our stockpile without either resorting to testing our stockpile or pursuing a modernization program.”

Our current nuclear arsenal is a relic of the Cold War, ill-suited for today’s multi-polar, increasingly proliferated world. We need to be modernizing our arsenal to address this reality, developing new nuclear warheads and delivery systems. And we certainly need to be able to test our arsenal to ensure its military effectiveness in the future.

But instead of helping meet today’s new and evolving security threats, the CTBT would have the United States ignore them. Instead of facing up to real security challenges, CTBT advocates assume the mantle of “moral leadership” and repeat their commitment to no testing and a world without nuclear weapons.

If testing options are eliminated, our military will have no choice but to “walk in faith” — faith that the most powerful weapons in the world will work for time eternal once the treaty enters into force. That’s a dangerous proposition. The United States relies on computer modeling to predict the effects of attrition and radiation on over a thousand components of a nuclear weapon. These components must all work together with split-second precision. But computers cannot take into account all the long-term structural changes caused by radiation, attrition, or the replacement of components under the aegis of the Life Extension Programs.

CTBT has a trust problem, as well. It’s impossible to verify compliance with the treaty. One can’t, for example, distinguish between a nuclear explosion and other seismic events, especially when states conduct low-yield tests. Yet low-yield tests could help cheating countries develop new nuclear weapons that would render our nuclear arsenal obsolete.

This problem is exacerbated by the fact that the treaty does not clearly define a nuclear-weapons test. The U.S. adheres to a zero-yield “no bang” standard. Russia and China claim low-yield weapons tests are permissible under the treaty.

The U.S., our allies, and our foes must be confident that our nukes will perform as advertised. These weapons provide the essential deterrence from attack against the homeland, Europe, South Korea, and Japan. Loss of U.S. credibility here can only fuel further proliferation of nuclear weapons. Some leaders have already begun to question our commitment to extending the nuclear umbrella to our allies. In February, the governor of Tokyo said Japan should develop nuclear weapons to protect itself from China and North Korea.

In 1999, the U.S. Senate properly rejected the CTBT on the grounds that it would jeopardize U.S. national security. Since then, security challenges have become far more complicated. Today, ratification is an even worse idea.

Owen Graham is research coordinator, and Michaela Bendikova is research assistant for missile defense and foreign policy, at the Heritage Foundation