to look to missile defenses to help insulate the United States from ballistic missiles and nuclear weapons proliferation. The npt, which is well-intentioned and may have dissuaded some states from pursuing nuclear weapons, is in dire need of an overhaul. It is rife with loopholes, such as allowing a wide range of nuclear activities closely related to nuclear weapons work. The accord also lacks the requisite teeth to ensure enforcement. North Korea threatened to leave it and then did so with its requisite 90-day notice before its 2006 nuclear test; Tehran ignored its tenets for 20 years before its nuclear activities were disclosed, not by the npt 's Praetorian Guard, the iaea, but by an Iranian dissident group.

The proliferation of ballistic missiles is not prohibited by any international treaty. The mtcr is a volunteer organization, which has been weakened over time by states that have flouted its principles when advantageous for hard currency, military assistance, or strategic influence. As a result, in recent years, the United States decided that leaving itself deliberately vulnerable to any weapon system or state — as it did during the Cold War — was foolish. Deliberate vulnerability can lead to perceptions of weakness, inviting provocation or aggression. In addition, it can lead a potential adversary to use threats, intimidation, blackmail, or coercion to achieve its objectives. In a day of seemingly unstoppable proliferation, the chance that horrific weapons will be used against peaceful nations is a troubling possibility.

Every state has an undeniable right to self-defense. It only makes sense that all reasonable, necessary steps are taken to protect and advance one's national security, especially if the technological capability is emerging to do so, as evidenced by tens of successful missile defense tests. Hitting a bullet with a bullet in the atmosphere, or even space, is now possible. Developing and deploying missile defenses is not about the missile or wmd threat from a single country or even several countries. Missile defense is about protection from these weapons no matter where the threat comes from now — or in the future.

And despite the range of concerns about missile defense, it should be emphasized that it is a defensive — not offensive — weapon. Indeed, the missile defense interceptor warhead does not even contain an explosive charge; traveling at 15,000 miles per hour, it destroys the missile warhead by the sheer force of the collision. Missile defense is like an umbrella; it is needed only if it rains. It threatens no one. It only undermines the capability of one country to threaten or attack another country with its ballistic missiles or wmd. The idea that the deployment of missile defense will provoke an attack is a canard meant to encourage passivity.

The United States has made it clear to concerned states that missile defense does not threaten their security, emphasizing that it is part of an expanding effort to counter the growing ballistic missile threat — wherever it comes from. Of course, no country should expect to have a veto over America's security. Indeed, those states that oppose missile defense would do better to turn their protests toward Tehran and Pyongyang and other capitals that are driving the need for it with their growing offensive ballistic missile capability, their own missile production, or their proliferation practices. Moreover, some security analysts speculate cautiously that the successful deployment of an effective missile defense may one day convince countries that their pursuit of missiles and wmd  should be abandoned as futile endeavors, supporting widely accepted nonproliferation goals.

Cold War-like mutually assured destruction or massive retaliation should not be the only options for policymakers. In the end, it is clear: Missile defense will improve America's security against the growing challenge of ballistic missiles and their unconventional payloads.