The news about the successful missile defense test conducted Friday by the Defense Department came at an opportune moment. Not only do we have constant reminders from North Korea and Iran of the importance of this program, but the program itself has been in real need of a boost, because congressional appropriations have been lagging. 

As the Bush administration has been focused on urgent foreign policy matters elsewhere, the lingering constraints of the defunct Anti-Ballistic Missile Treaty continue to hamstring the program. Yet, in terms of overall defense and counter-proliferation objectives, the capacity to intercept incoming missiles from space remains crucially important for the United States. 

Friday's test simulated an attack by a North Korean long-distance Taepodong 2 missile. This is particularly appropriate since North Korea defiantly has continued to test this missile, recently with the provocative timing of July 4th. North Korea, further, is one of the main proliferators of missile technology, which means that the Taepodong is a type we might well encounter elsewhere. 

The U.S. fired dummy missile from Kodiak Island, Alaska, at 1:22 pm. It was destroyed by a missile interceptor fired from Vandenberg Air Force Base in California 17 minutes later, after having been tracked by ground and sea based radars. 

The test simulated an intercept in the mid-phase of a missile attack, which is the most difficult, as the missile at this point has gained the greatest height. Though the first successful test in several years, it is the sixth success of the Ground-based Midcourse Defense (GMD) system since 1999, a stunning technological feat, with missile and interceptor traveling at 15,000-18,000 mph. This is what is meant by the phrase "hitting a bullet with a bullet." 

With North Korea and Iran digging in their heels, determined to preserve their nuclear options and expand their missile capabilities, it is crucial that the United States continue to pursue both a deterrent and a convincing missile defense -- and that we share the shield with our allies abroad. The strategy of rogue states is based on the threat of nuclear missiles that can be used for blackmail, enhancing their regional influence and their international standing. Their nuclear know-how can find its way into terrorist hands, and their missiles are a very real threat to those within their reach, particularly Israel and South Korea. 

Without nuclear weapons, Iran would remain a significant player in the Middle East, albeit much less dominant. And without its nuclear program, North Korea would be little more than a militarized concentration camp, a threat to stability on the Korean Peninsula, but nothing more. Other aspiring regional autocratic players like Venezuela's Hugo Chavez are taking lessons from the North Korean and Iranian playbooks. 

It is, of course, hardly likely that either Iran or North Korea would choose to attack the United States directly as their own sure nuclear annihilation would follow. If, however, missile defense covered strategic areas of the globe, their power to blackmail and their influence would be vastly reduced. 

Critics of missile defense were quick to play down the significance of the test, of course. For one thing, according to the less-than-glowing report in The Washington Post, the test lacked the element of surprise -- an inevitable factor that would invalidate every weapons test conceivable. Another criticism was that the missile carried just one warhead, suggesting that in a multiple warhead launch, some would get through. 

It is true that the ground-based mid-course defense system that the United States has been building in Alaska and California is too limited in scope. The United States currently has a grand total of 11 land-based interceptors. In addition, according to Gen. Henry Obering, director of the Missile Defense Agency, in congressional testimony last spring that the United States has just 10 interceptor missiles aboard AEGIS cruisers. As encouraging as the success of Friday's test is, this is clearly too thin a defense. What we have is known as a "limited defense capability," and it is clearly that. 

Though ground- and sea-based defenses can handle limited local threats from a known source, it is clear that far more needs to be invested in the missile defense program and that ultimately the most comprehensive and effective defense will be based in space, possibly based on the Brilliant Pebbles concept, which was abandoned during the first Bush administration. 

Dealing with aspiring nuclear players multilaterally has so far led to little more than a stalemate. In this context, missile defense is a strategic card the United States should be able to play with increasing confidence.

Helle Dale is director of the Douglas and Sarah Allison Center for Foreign Policy Studies at the Heritage Foundation.