An interceptor missile fired from a silo at Vandenberg Air Force Base in California in a test of the backbone of U.S. ballistic missile defense failed to hit a target missile over the Pacific today, the Pentagon said.

The miss is likely to raise questions about the reliability of a U.S. ballistic missile defense system the U.S. Government Accountability Office said has received $90 billion in funding since 2002.

  The Missile Defense Agency, U.S. Air Force 30th Space Wing, Joint Functional Component Command, Integrated Missile Defense and U.S. Northern Command conducted the flight test of the what’s known as the ground-based mid-course defense element of the nation’s ballistic missile defense system.

Mobile and ship-based missile defense systems also are part of the mix.

“Although a primary objective was the intercept of a long-range ballistic missile target launched from the U.S. Army’s Reagan Test Site on Kwajalein Atoll, Republic of the Marshall Islands, an intercept was not achieved,” the Pentagon said in a release.

“Program officials will conduct an extensive review to determine the cause or causes of any anomalies which may have prevented a successful intercept,” the Pentagon said.

The $2 billion Sea-Based X-Band Radar, which is normally berthed at Pearl Harbor’s Ford Island but left port weeks ago, was to provide tracking for the test, officials said.

Ground-based interceptors have hit their targets in just eight of 16 tests, with the most recent successful test in 2008.