A Japanese navy ship failed to shoot down a mid-range ballistic missile target in a test off the coast of the Hawaiian island of Kauai, the US Missile Defense Agency announced.
It was only the second time Japan had attempted to shoot down a ballistic missile from a ship at sea. The first attempt last year was successful.
In Wednesday's test, a ballistic missile target launched from the Pacific Missile Range Facility at Barking Sands on Kauai was detected and tracked by the crew of the JS Chokai.
Three minutes later, the Japanese destroyer fired an interceptor missile to shoot down the target in space, but the intercept failed.
"There is no immediate explanation for the failed intercept attempt. More information will be available after a thorough investigation," the agency said.
The performance of the Japanese crew was rated "excellent," it said.
The joint test followed a similar test last December, when the JS Kongo, another Japanese destroyer, intercepted a ballistic missile target fired from the facility on Kauai.
US Navy ships and the Missile Defense Agency have together conducted over a dozen successful ballistic missile intercepts in tests off Hawaii. Wednesday's test offered the Japanese navy a chance to verify the technology on board its own ship.
"This is a test for our allies to help build their confidence and understanding of their system," Mary Keifer, Lockheed Martin's director for international ballistic missile defense programmes, had said before the test.