Leftists tend to believe that stem cell research can solve humanity's ailments and scientists can accurately predict global climate changes, yet somehow they have trouble grasping that missiles can be intercepted and destroyed.

The United States can and is doing just that.

Despite an attempt by the Clinton Administration to dismantle key components of our national security, missile defense is now coming to fruition.

The past few years have seen a steady progress of successful tests and improvements to the system. Does this still sound like "trying to hit a bullet with a bullet?"

"Many people think that missile defense is only the long-range interceptor system now being deployed in Alaska and California, but it is much more than that," said Lt. Gen. Henry Obering III, director of the Missile Defense Agency. "We currently have 17 major missile defense elements."

These 17 defense elements are designed to destroy a missile during its boost, mid-course and terminal phases. The program incorporates assets from all branches of the military, civilian employees and contractors, as well as land, air and sea based defense systems.

A classic line from critics is that a missile defense system would upset our allies. Quite to the contrary, our allies are thrilled by the prospect of being covered by regional missile defense shields, without having to endure the massive research and development costs.

Allies like Britain, Israel, Poland, Japan and the Czech Republic have all agreed to participate in development of regional missile defense systems, and why wouldn't they?

Critics also argued that the possibility of a "dirty bomb" attack would render a missile defense system worthless. Although the threat of a dirty bomb attack is a real one, as the Islamic terrorist Jose Padilla's foiled attempt showcased, the existence of one threat doesn't make the other disappear.

The Missile Defense Agency said that although the end of the Cold War reduced the likelihood of a global nuclear conflict, an increase in technology on an international level has made sophisticated missile technology more readily available to less developed enemies of the United States.

The White House said that "curbing the flow of missiles and related technology to proliferators ... and missile defenses play complementary roles in countering the global missile threat."

North Korea and Iran (and previously Iraq) are all developing advanced missile technology that could be used to deliver conventional or unconventional weapons. These regimes are defying the international community in order to acquire the capability to use nuclear blackmail. The United States isn't over-reacting to want such a defensive system.

Some point to Russian president Vladimir Putin's statements of opposition to the deployment of missile defense systems in Europe as evidence that missile defense is bad for diplomacy.

However, missile defense systems are purely defensive and have no offensive capability. Unless Russia plans on firing its missiles into Europe, this doesn't directly affect them at all. And the idea that this will create an "arms race" is absurd given that Russia doesn't have the resources to develop anything close to the United States' systems.

Russian saber rattling over missile defense in Europe is not the source of deteriorating relations with Russia. Turning a Russian weakness into a posture on a moral high ground is a symptom of Putin's opportunism.

The key here is deterrence: Would Iran and North Korea be more or less likely to continue developing advanced missile technology if they knew the United States could essentially nullify it?

A successful missile defense system would frustrate our enemies, be welcomed by our friends and have the capability to prevent nuclear missiles from obliterating tens of millions of Americans. As Mastercard commercials say: that's priceless.

[Reach columnist James Foxcurran at opinion@thedaily.washington.edu.]