A Japanese naval destroyer failed to intercept a dummy ballistic missile in a test aimed at mimicking an intermediate-range North Korean ballistic missile attack, the US and Japan announced.

'There is no immediate explanation for the failed intercept attempt,' military officials from both countries said in a joint statement.

The test took place in Hawaiian waters and involved the Chokai, the second Japanese Kongo-class ship to be outfitted by the United States for missile defense.

North Korea's test-firing of a ballistic missile over Japan in August 1998 spurred Tokyo to become the most active US ally in building a layered shield against missiles that could be tipped with chemical, biological or nuclear warheads.

The drill off Kauai, Hawaii, used the ship-borne Aegis ballistic missile defense system made by Lockheed Martin Corp and a Standard Missile-3 Block 1A missile, built by Raytheon Co.

The operation of the Aegis weapon system by the Chokai's crew and the missile's 'flyout' toward the target were successful even though the intercept was not achieved, said Rear Adm. Tomohisa Takei, operations and plans director for the Japanese Maritime Self Defense Force, and US Air Force Lt. Gen Henry Obering, head of the Pentagon's Missile Defense Agency.

More information will be available after a thorough investigation, they added in their statement.

The Missile Defense Agency, which staged the event in cooperation with Japan's Maritime Self-Defense Forces, called it a 'No Notice' test, more challenging than the first of its kind for a Japanese ship in 2007.

To make it more realistic, the time of the target's launch from a range on Kauai was not disclosed to any participants, the Pentagon said in a 'fact sheet' before the test.

Also, the target warhead separated from its booster rocket, increasing the challenge of picking out the re-entry vehicle, the Pentagon said.

In addition to the Chokai, a similarly equipped US Navy destroyer, the Paul Hamilton, was to have tracked and performed a simulated engagement against the ballistic missile. There was no immediate word on its performance.-Reuters