As the debate about U.S. missile defense unfolds, it is important to remember the basics of leadership and vision. An example of the opposite -- timidity and shortsightedness -- is the recycled Cold War argument of Philipp C. Bleek and Frank N. von Hippel in their Dec. 12 op-ed piece ["Missile Defense: A Dangerous Move"].

The writers argue that "cooperative efforts" toward international security would be "derailed by a U.S. decision to go it alone in pursuit of illusory defenses." That theory, never very compelling, is entirely unpersuasive today, when we face a burgeoning missile threat and have effective defenses against it within our grasp.

Their argument against missile defense rests on two principal points. First, they contend, attacks by rogue states such as North Korea or Iran are improbable. "The desire for prestige and bargaining leverage may motivate North Korea and Iran to acquire intercontinental ballistic missiles," they write. "But these missiles are unlikely vehicles for a deliberate nuclear attack -- unless a country wants to commit suicide."

If indeed an increasing number of rogue states see missile capability as useful for blackmail and coercion, you might think that would be enough to spur American leaders to take steps to diminish that leverage and clout. Moreover, missile defense is not just about protection from "deliberate" attacks. It would be egregiously irresponsible not to defend against an equally deadly accidental launch.

But why are Bleek and von Hippel convinced that a deliberate attack by a rogue state is so unlikely? The bipartisan Rumsfeld Commission, which released its sobering report on ballistic missile threats in July 1998, concluded that a number of nations are working to acquire "ballistic missiles with biological or nuclear payloads." A rogue nation, the commission concluded, could have the capability to strike the United States in as little as five years.

The consensus on the Rumsfeld Commission's findings has only broadened since it came out. The 1999 National Intelligence Estimate (NIE), representing the combined judgment of all U.S. intelligence agencies, underscores the fact. The NIE states that "the proliferation of medium-range ballistic missiles -- driven primarily by North Korean No Dong [missile] sales -- has created an immediate, serious, and growing threat to U.S. forces, interests, and allies, and has significantly altered the strategic balances in the Middle East and Asia."

Still, Bleek and von Hippel argue that the missile threat is overblown. They are concerned that missile defense is not foolproof. An attacker, after all, could still carry out an assault with a "boat or a civilian aircraft." What's more, the missiles of an adversary "would certainly be equipped with countermeasures" so that a missile, even one launched accidentally, "could penetrate the system."

Of course no defense system is ever infallible. Nor is missile defense intended as a means of dealing with the full spectrum of threats facing the United States. But this is an argument for doing nothing. The ballistic missile threat continues to be the primary threat facing the United States. Ballistic missiles are a cost-effective delivery system: Whether short- or long-range, they carry a high probability of delivering their payload to a target.

In the hands of the wrong people, moreover, they become a powerful geopolitical weapon. Would the United States and its allies have liberated Kuwait if Saddam had possessed an intercontinental ballistic missile with a nuclear warhead?

What about countermeasures? To every measure there is a countermeasure, to be sure. But America's strength is the immense and growing technological edge it has on its adversaries, real and potential. We may never be perfectly invulnerable, but the right missile defense system will considerably lower the risk of a missile's reaching the United States.

Bleek and von Hippel cite Russian, Chinese and European objections to a missile defense. "The most effective protection against nuclear weapons," they write, "is to strengthen the nuclear nonproliferation and disarmament regime."

It's true the Russians and Chinese object to current U.S. plans, and that our allies worry about a new arms race. But China and Russia know they have nothing to fear from American missile defense. The United States pursues cooperative policies toward both. Can anyone imagine how either China or Russia would profit by turning its back on the West? Moscow once opposed German unification and NATO expansion, too. But confidence and conviction on our part proved ultimately persuasive, and the sky did not fall.

There is no evidence to suggest that constructive arms control and nonproliferation policies are incompatible with prudent steps toward missile defense. It's time to leave the old Cold War thinking behind and get on with the task of defending the American people and our allies.

Jeffrey Gedmin is a resident scholar at the American Enterprise Institute. Jon Kyl is a Republican senator from Arizona and a member of the Senate Intelligence Committee.