Online Special: National Missile Defense Feb. 2, 1998: Questions and Answers on the National Missile Defense Shield..

"The Ballistic Missile Defense Organization (BMDO) announced today that it has successfully completed a test involving a planned intercept of an intercontinental ballistic missile target," the U.S. Defense Department said in a statement. The planned intercept of an intercontinental ballistic missile target is part of President Bush's plan to build a shield that would protect the United States from ballistic missiles launched by "rogue nations" such as Iraq and North Korea. Two rockets were used in the test. The first, launched from a Minuteman-2 at Vandenberg Air Force Base in California, carried a dummy warhead and a decoy balloon. Ground-based radar followed the progress of these objects and guided a second rocket — the interceptor, or "kill vehicle" — to the warhead. The kill vehicle was launched 20 minutes after the initial rocket, from Kwajalein Atoll in the South Pacific's Marshall Islands. It approached the dummy warhead at 15,000 miles per hour, intercepting it about 10 minutes after its launch. The kill vehicle then intercepted the dummy warhead over the central Pacific Ocean, at an altitude of roughly 140 miles above the earth. The test, twice postponed due to bad weather, marks the third successful shoot-down out of a five attempts. Inclement weather made it impossible to continue because the Pentagon's safety rules state that the sky must be clear enough to allow visual tracking of the intercepting missile. In a wartime situation, the interception would progress regardless of poor visibility. However, some scientists have questioned the system's effectiveness in bad weather. Other critics have focused on the high price tag of the tests -- at nearly $100 million apiece. The Bush administration has responded with reassurance that the trials are absolutely necessary to the development of the missile defense shield. Both Russia and China have expressed opposition to the U.S. plan to develop the shield. The two countries believe it would breach the 1972 Anti-Ballistic Missile (ABM) Treaty and could spark a new arms race.