The test aimed to check how well a Japanese-designed clamshell nose cone separated from a U.S.-designed interceptor missile. It was the first U.S. missile defense flight test to use Japanese parts.

The USS Lake Erie guided missile cruiser fired a Standard Missile-3 interceptor into the atmosphere above the Pacific about 60 miles northeast of Kauai, the U.S. Missile Defense Agency said in a news release.

There was no live target for the interceptor missile. Instead, the SM-3 aimed itself at a simulated target inserted into Aegis Ballistic Missile Defense program computers.

Cameras mounted on the missile recorded the Japanese clamshell nose cone separating from the warhead.

The new style of nose cone allows the missile's warhead to spot its target more quickly, shortening the time the interceptor missile's warhead needs to shoot down its target.

Today's test also aimed to show how well the nose cone works with the U.S. military's sea-based, or Aegis, ballistic missile defense program.

The United States and Japan started jointly researching ballistic missile defense technology in 1999, one year after North Korea test-fired a long-range missile over northern Japan.

Pyongyang's surprise test alarmed Tokyo and spurred a strong Japanese interest in missile defense.

In 2003, Japan became the first U.S. ally to buy elements of the U.S.-designed missile defense system when it upgraded Aegis radars already on board its naval destroyers. Japan also bought SM-3 interceptors from the United States.

Japan's Defense Agency is also planning to buy 124 Patriot surface-to-air missiles by 2010.

Today's test follows a successful test off Hawai'i in November, when the Missile Defense Agency and the Navy intercepted and destroyed a warhead as it separated from its booster rocket.

That test marked the first time a ship at sea has shot down a multistage missile.

It also marked the Aegis ballistic missile defense system's sixth successful interception in seven attempts since 2001.

A sea-based test failed in 2003 when an interceptor missile missed its target.