Key U.S. missile interceptor test fails, Pentagon says WASHINGTON (Reuters) - A test of the only U.S. defense against long-range ballistic missiles failed on Friday, the third consecutive failure involving the interceptor system managed by Boeing Co, the Defense Department said. "Program officials will conduct an extensive review to determine the cause or causes of any anomalies which may have prevented a successful intercept," it said in a statement. The military has tested the so-called ground-based midcourse defense system 16 times. It has succeeded eight times, with the last intercept in December 2008. The Pentagon said this week that the test would not affect its decision to bolster the U.S. missile defense system. Defense Secretary Chuck Hagel announced the move in March following threats by North Korea. Under that plan, the Pentagon will add 14 new anti-missile interceptors at a total cost of nearly $1 billion. The United States currently has 26 interceptors deployed at Fort Greely in Alaska and four at Vandenberg Air Force Base in California. In Friday's test, a long-range ballistic missile target was launched from the U.S. Army's Reagan Test Site on Kwajalein Atoll, Republic of the Marshall Islands. The interceptor missile was launched from Vandenberg Air Force Base. Reporting by Phil Stewart; Editing by Xavier Briand