General Victor Renuart Jr., senior commander for defense of United States territory, said that while the system is still being upgraded with additional radars and interceptors, it can already guard the U.S. West Coast against a limited attack from Asia. 

As more components come online in California and Alaska, the system will be able to protect larger areas from more complex attacks.

When first proposed, critics originally called the system "Star Wars" and derided "Ronnie Raygun's" scheme as scientifically impossible. Despite repeated criticism, research development that began shortly after Reagan's 1983 speech continued.

Early work focused on exotic beam weapons to knock out incoming missiles. But the development of ultra-high-speed electronics soon enabled the approach used today- - the EKV, or Exoatmospheric Kill Vehicle. The EKV collides directly with incoming missiles, using its own kinetic energy to destroy the target, an approach described as "hitting a bullet with another bullet."

Renuart claims the system, while operational, still has not received the military's claim of "fully operational." He claims in July 2006 parts of the system were tested as North Korea staged missile testing around that time. 

Raytheon reported successful test interceptions on five separate occasions since October 1999.

The most recent test was held last Friday.  A target missile was launched from Kodiak Island, Alaska, and tracked by radar at Beale Air Force Base, outside of Sacramento. The interceptor was launched from Vandenberg Air Force Base, near Santa Barbara, California, and scored a direct hit.

Shortly after the testing, Lieutenant General Henry Obering III, director of the Missile Defense Agency, said, "Does the system work? The answer is yes to that."

Plans for European expansion of the system call for missile interceptors in Poland and a tracking radar in the Czech Republic to defend against the threat of Middle Eastern ballistic missiles.