An interceptor missile launched from California on Wednesday failed to hit a target fired from a Pacific atoll 4,000 miles away during a test of an anti-ballistic missile defense system, the Air Force announced.

The missile, called a ground-based interceptor, lifted off from coastal Vandenberg Air Force Base at 12:03 a.m. and released a device called an Exoatmospheric Kill Vehicle, or EKV, that was to plow into a target missile fired from the Kwajalein Atoll in the Marshall Islands.

The interceptor's sensors worked and the EKV was deployed, but it missed, according to a statement from Rick Lehner, a spokesman for the U.S. Missile Defense Agency.

The cause of the failure will be investigated before another test is scheduled, Lehner said.

It was the fourth launch of a fully operational interceptor from Vandenberg, 130 miles northwest of Los Angeles. The $100 million launch originally was planned for Tuesday, but it was delayed by poor weather.

The missile agency noted that the Sea-Based X-Band Radar, a critical component of the system, performed as planned. The radar, which cost more than $800 million, is mounted on an oceangoing-platform that can sail to any point where the military needs to track missiles. The 280-foot-tall radar can identify baseball-size objects thousands of miles away. It was built by Raytheon Co. for the Boeing Co., the prime contractor on the project.

Ground-based interceptors are in place at Fort Greeley, Alaska, in addition to Vandenberg.

In recent years the military has held a series of tests of technologies to defend against long-range ballistic missiles that might be fired from countries such as North Korea.

Other components of the missile shield could include sea-launched missiles and lasers mounted in planes.