On December 15, the Missile Defense Agency conducted an unsuccessful test of Ground-Based Midcourse Defense (GMD), a long-range ballistic missile defense system designed to protect the U.S. homeland against a missile threat from North Korea or Iran.

The initial review suggests that the failure occurred because an undetermined problem with the newest kill vehicle configuration. A more detailed review of why the GMD system failed to intercept and destroy the target has been initiated.

However, it is important to note that while the intercept itself was a failure, the first two stages of the interceptor performed extremely well. Indeed, the Sea-Based X-Band radar (SBX) and all sensors performed as planned. The SBX was a cause in the failure of a test conducted earlier this year.

The failure of this recent test does not mean that the United States is unable to develop or field capability that would protect it against a North Korean or Iranian long-range ballistic missile attack. The GMD system is very complex, and a network of sensors, command, control, and communications spans half the globe. It is appropriate to note that many of the critics of missile defense oppose the program because they view missile defense as complicating the arms control and disarmament agenda they support. For them, this test failure has nothing to do with their opposition to the program. Indeed, they would likely see a successful test as a stronger reason for terminating the program than a failed one.

There are important lessons to be learned. The scientists, engineers, and contractors working on an advanced technology program can learn more from failed tests than from successful ones. The proper response to a failed test is to maintain a robust program that applies the lessons from the failure to advance the program in the future. Up to date, the testing program for the GMD system has been too timid because of concern about negative political reaction to any such failure and inadequate testing budgets. Under this timid approach, the opportunities for dramatic advances in technology are very limited.

The program must not be canceled, as the U.S. would eventually be left vulnerable to attacks with long-range ballistic missiles. It is intolerable that the American people would remain so vulnerable. The GMD program needs to continue, and the companion sea-based ballistic missile defense systems should be advanced to give them the capability to counter long-range missiles for the defense of U.S. territory. Currently, the sea-based systems have been given the capability to counter only short- and intermediate-range missiles.

Finally, the U.S. should revive a program pursued during the Reagan and George H. W. Bush Administrations to develop and field space-based ballistic missile defense interceptors. All three steps are necessary if the federal government is going to meet its obligation to provide for the defense of the American people.