US shoots down mock warhead over the Pacific

WASHINGTON (AP) - The Pentagon says it has shot down a mock warhead over the Pacific in a success for America's missile defense program.

The military says an interceptor rocket launched from Vandenberg Air Force Base in California slammed into the warhead as it traveled outside the Earth's atmosphere after being launched from a test range on Kwajalein Atoll in the Pacific.

The test was the first of its kind in nearly three years. And it was the first test ever targeting an intercontinental-range missile like North Korea is developing.

The most recent intercept test, in June 2014, was successful, but the longer track record is spotty. Since the system was declared ready for potential combat use in 2004, only four of nine intercept attempts have been successful.

North Korea says its nuclear and missile programs are a defense against perceived U.S. military threats.

Laura Grego, senior scientist at the Union of Concerned Scientists, which has criticized the missile defense program, calls the interceptor an "advanced prototype," meaning it is not fully matured technologically even if it has been deployed and theoretically available for combat since 2004.

The interceptors are, in essence, the last line of U.S. defense against an attack by an intercontinental-range missile.

The Pentagon has other elements of missile defense that have shown to be more reliable, although they are designed to work against medium-range or shorter-range ballistic missiles. These include the Patriot missile, which numerous countries have purchased from the U.S., and the Terminal High-Altitude Area Defense, or THAAD, which the U.S. deployed this year to South Korea to defend against medium-range missiles from North Korea.