The Japanese destroyer Chokai will be in Pearl Harbor this weekend and off Kaua'i next week for the second test of Japan's ability to shoot down a ballistic missile target in the midcourse phase of flight.

Eighteen U.S. cruisers and destroyers and four Japanese ships are being outfitted with the Aegis ballistic missile defense capability.

The still-developing U.S. missile defense system includes shootdown capabilities targeted to the boost stage of flight, the midcourse in space, and terminal phase with re-entry into the atmosphere.

President-elect Barack Obama has not made clear his intentions with regard to missile defense, and in the past expressed some skepticism about the program.

The head of the Missile Defense Agency, Lt. Gen. Henry A. Obering, said the U.S. would be "severely hurt" if missile interceptors are not installed in Eastern Europe as planned.

Next week's sea-based test in the Pacific Missile Range Facility off Kaua'i will involve the Japanese ship Chokai and the Pearl Harbor-based destroyer Paul Hamilton.

The Missile Defense Agency said the test is intended to verify the engagement capability of the recently upgraded destroyer JS Chokai.

For the test, a ballistic missile target will be launched from Kaua'i. The Chokai will detect, track and engage the target with an SM-3 Block 1A missile during its midcourse phase of flight.

The radar system will have to differentiate between the separating booster and simulated warhead. About 500 Japanese and U.S. military and contractors are expected to be in Hawai'i for the test.

On Dec. 17, 2007, off Kaua'i, the Japanese destroyer Kongo shot down a ballistic missile target, marking the first time that an allied naval ship successfully intercepted a target with the sea-based Aegis weapons system.

On Nov. 1, during the exercise "Pacific Blitz," the destroyers Hamilton and Hopper fired SM-3 missiles at separate targets launched from Kaua'i.

Paul Hamilton scored a direct hit, while the missile fired by the Hopper missed its target, the Navy said.

The Aegis ballistic missile defense system has been successful in 16 of 19 attempts, officials said. The tests were the first overseen by the Navy and not the Missile Defense Agency.

Riki Ellison, chairman of the Missile Defense Advocacy Alliance, said the exercise represented a regional missile attack with the two Navy ships defending the countries that were targeted by the simulated ballistic missiles.

Ellison said the SM-3 fired by the Hopper failed to engage when a sensor used to "heat" seek did not cool properly, and as a result could not track the target missile.

"Both of the SM-3 missiles that were used were at the end of their life cycle and there was most likely a leak of coolant caused by aging," Ellison said after the test.

Under an actual attack, multiple shots of SM-3s from multiple ships would be made at each attacking missile to increase the chances of success, Ellison said.

The Aegis ships are capable of intercepting short- to intermediate-range ballistic missiles. The system also serves as a forward-deployed sensor by providing early warning of an intercontinental ballistic missile launch, according to the Missile Defense Agency.

The long-range tracking capability would assist in the defense of the U.S., including Hawai'i and Alaska, by providing tracking data to cue other system sensors and initiate a ground-based missile defense, the agency said.

Before returning to Japan, the Chokai will be loaded with additional SM-3 missiles, "ready to provide Japan with a proven midcourse engagement capability against the increasing ballistic missile threat present on that region," the Missile Defense Agency said.